JPH1060693A - Plating solution automatic management device - Google Patents

Abstract

(57) [Summary] Summary [Problem] In an automatic plating apparatus during plating operation, characteristic values such as the concentration and pH of one or more components in a plating solution are automatically measured, and the measured value is within a predetermined range. The present invention provides a plating solution automatic management method and apparatus for automatically calculating a replenishment amount of a correction reagent for correction when the deviation is out of range, and automatically replenishing the correction reagent. An automatic plating solution management method for automatically replenishing a correction reagent for managing a characteristic value of a plating solution in a plating tank in which a plating operation is performed so as to be maintained at a target value, A sample solution for measurement is collected from the plating solution at regular time intervals; the characteristic value is measured for the sample solution; the obtained measured value is compared with a preset target value, and (i) the measured value is set. If the value is within the range of the value, the processing ends, and (ii)
When the measured value is out of the range of the set value, the correction data is calculated; in accordance with the correction data, a correction reagent is replenished so that the characteristic value of the plating solution in the plating tank becomes the set value.
An automatic plating solution management method having a process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, partial plating of silver, strike plating of silver or copper, the concentration of a plating film component in a plating solution, the concentration of free cyanide and the p.
H is automatically measured, and based on those measured values, the replenishment amount necessary to correct the concentration and / or pH of the plating film component and free cyan to a predetermined value is automatically calculated and replenished. The present invention relates to a liquid automatic management method and an automatic management device.

[0002]

2. Description of the Related Art In electronic components such as ICs, LEDs, and transistors, lead frames for forming circuits include:
A silver portion is applied to a pad portion on which a semiconductor chip is mounted and a lead portion for performing wire bonding. Prior to the partial plating of silver, copper or silver is used as a base for the partial plating film in order to make the appearance of the partial plating film uniform and to improve the adhesion of the plating film to the lead frame. Strike is applied.

When performing partial plating of silver or strike plating of copper or silver, an automatic plating apparatus is used. In these automatic plating apparatuses, the concentration of a plating film component such as silver or copper, the concentration of free cyanide, and the pH continuously change with the operation.

[0004] In order to maintain the quality of the plating film in a good range, it is necessary to maintain the composition and pH of the plating solution within predetermined ranges. For this reason, conventionally, the concentration of the coating film component, the concentration of free cyanide and the pH are periodically measured, and when the measured values of these characteristics deviate from the predetermined ranges, the replenishment amount of the predetermined chemical is determined based on the measurement results. Is calculated, supplemented, and corrected.

[0005] In other plating processes, substantially the same operation is performed.

[0006]

The above-mentioned concentration and pH are measured, and the replenishing amounts of the respective chemicals are calculated based on the measured results, and the replenishing operation has conventionally been performed manually. And spend time. In particular, when a plurality of automatic plating apparatuses are operating, unless rapid measurement is performed by a skilled person, a large fluctuation occurs in the plating solution, and as a result, the quality of the plating film is greatly reduced. Invite.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an automatic plating apparatus during plating operation in which the concentration or pH of one or more components in a plating solution is adjusted. Automatically measure the characteristic values such as, if the measured value is out of the predetermined range, automatically calculate the replenishment amount of the correction reagent to correct the characteristic value to the predetermined range, and automatically It is an object of the present invention to provide a method and apparatus for automatically controlling a plating liquid to be replenished.

[0008]

According to the present invention, a correction reagent is automatically replenished in order to manage the characteristic value of a plating solution in a plating tank in which a plating operation is performed so as to be maintained at a target value. A method for automatically controlling a plating solution, wherein a sample solution for measurement is collected from the plating solution at regular time intervals; the characteristic values are measured for the sample solution; and the obtained measured values are preset. Comparing with the target value, (i) if the measured value is within the set value range, end the process; (ii) if the measured value is outside the set value range, calculate the correction data; There is provided an automatic plating solution management method including a step of replenishing a correction reagent so that the characteristic value of a plating solution in a plating tank becomes a set value according to the correction data. This method
As shown in FIG. 1, means (A) for collecting a sample liquid for measurement from the plating tank; means (B) for measuring the characteristic value of the sample liquid; and the measured values obtained are set in advance. Means (C) for comparing with a target value and calculating correction data when the measured value is out of the range of the set value; and the calculating means so that the characteristic value of the plating solution becomes the set value (range). A control means (D) for controlling the next replenishing means (E) in accordance with the correction data obtained by (1) to adjust the replenishment amount of the replenishing correction reagent; and replenishing the correction reagent to the plating solution in the plating tank. Means (E), and can be carried out using an automatic plating solution management apparatus that automatically replenishes a correction reagent so that the characteristic value of the plating solution is maintained at a target value.

The present invention can be basically applied to all plating processes, and typical examples include partial plating of silver and strike plating of copper or silver as exemplified below. It can also be applied to the management of the plating solution.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The characteristic values in a plating solution to be measured include the concentration of plating film components, for example, the concentration of silver and copper, the concentration of free cyan which affects plating performance, and the pH of a plating solution. Can be

The means for collecting the sample solution from the plating tank usually comprises a pipe for collecting the sample solution and transporting it to the measuring means, a pump for providing transport power, an appropriately arranged valve, and the like. Preferably, a liquid storage tank is provided in the middle, and the sample liquid collected from the plating tank is stored in the liquid storage tank, and the required amount is transported to each measuring means of the plating film component concentration, free cyanide concentration and pH. When the liquid storage tank is provided as described above, it is preferable to provide a means for collecting the excess sample liquid remaining in the liquid storage tank in the plating tank.

The measuring means basically comprises a measuring tank for storing a sample liquid for measurement and electrodes for measuring characteristic values. As the electrode for measurement, a known electrode can be used. For example, so-called pH is used as an electrode for measuring pH.
Glass electrodes known as meters can be used. As the electrodes used for measuring the silver concentration, the copper concentration, and the free cyan concentration, known solid model ion electrodes can be used, and are commercially available from, for example, Toa Dempa Kogyo Co., Ltd., Electrochemical Meter Co., Ltd. Can be used.

Further, the concentration of the plating solution is generally too high for measurement with an electrode, so that it is diluted if necessary. Therefore, means for supplying a diluent suitable for each measuring tank is provided.

The pH measuring tank is provided with a diluting water supply means for diluting the sample solution to about 1 to 10 times.

In the free cyanide concentration measuring tank, 10
In order to dilute the solution to about 00 times and to set the free cyanide concentration on the order of ppm, a supply means for a buffer for dilution and / or a dilution water is provided. Usually, a buffer, for example, a NaOH / Na ₂ CO ₃ -based or phosphate-based buffer is used to maintain the pH of the sample solution at 9 to 12. Dilution water is used as needed.

The plating film component concentration measuring tank is also provided with a buffer liquid supply means having a pH of about 6 to dilute the sample solution to about 1000 times. As the buffer, for example, a phosphate buffer is used.

Further, in the plating solution, silver or copper is a stable cyanide complex (KAg (CN) ₂ or K ₂ Cu (C
Since N) ₃ ) is formed, the concentration cannot be measured with the above electrodes as it is. Therefore, the tank for measuring the silver concentration and the copper concentration is provided with an acid (nitric acid and sulfuric acid) supply means and a heating means such as a heater for decomposing the cyan complex salt. As a measurement procedure, a mixture of nitric acid and sulfuric acid is added to a sample solution collected from the plating tank in an amount of about 2 to 3 mL, and the mixture is heated to about 80 to 200 ° C. by a heater. In this way, silver and copper become forms that can be sensed by the electrodes,
Before the measurement with the electrodes, the sample is cooled to room temperature and diluted with the buffer solution to an appropriate concentration. Therefore, the coating component concentration measuring tank is provided with cooling means.

The above-mentioned supply means for water, buffer and acid for dilution comprises a tank for storing the water and the reagent, and a device for supplying the water or the reagent from the tank to a predetermined measuring tank. Have been.

The arithmetic means (C) and the control means (D) constitute a computer.

In the calculating means (C), target values of characteristic values, concentrations and pH values to be controlled are set in advance. Alternatively, the target value may be set for each measurement from the characteristic value setting means (F).

Appropriate component concentrations and pHs of various plating solutions are known to those skilled in the art. For example, the target value is set approximately in the following range.

(A) Silver strike plating solution: KAg (CN) ₂ to 1 g / L KCN 100 to 150 g / L pH 10 or more as silver content (b) Copper strike plating solution: K ₂ Cu (CN) ₍₃ ) 20 to 50 g / L KCN for copper content 10 to 50 g / L pH 10 or more (c) Partial silver plating solution: KAg (CN) ₂ 50 to 90 g / L KCN for silver content 1 to 5 g / L pH 8 to 10 The measured value sent from the measuring means (B) is compared with the set value. Since the film component concentration and the free cyan concentration are measured in a diluted state, the measured value multiplied by the dilution ratio is compared with the set value. Thus, the correction data corresponding to the difference between the set value and the measured value is calculated,
The data is sent to the control means (D). Control means (D)
Controls the correction reagent replenishing means on the basis of the correction data sent from the calculating means (C) so that the reagent required for the correction is supplied to the plating tank.

The replenishing means (E) includes, for example, a replenishing solution tank for storing a concentration of a plating film component to be replenished, a concentration of free cyanide and a correcting solution for pH, a pipe for transferring the correcting solution from the replenishing solution tank to the plating tank, And a valve provided on the pipe and capable of controlling opening and closing, and the opening and closing of this valve is controlled by the control means (D).

The reagent added by the replenishing means (E) is the same as that conventionally used, for example, the following.・ Correction of pH: sodium hydroxide and potassium hydroxide in silver and copper strike plating solutions. In this case, it is added so that the pH may be maintained at a predetermined value or more.

In the silver partial plating solution, phosphoric acid, nitric acid, citric acid and the like are used. It is necessary to keep the pH within a certain range, but since the pH usually rises during the plating operation, an acid is added so as not to exceed the constant pH.・ Correction of film component concentration: As plating work progresses,
The coating component concentration naturally decreases. The aforementioned cyan complex salt is added. -Correction of free cyan concentration: Free cyan in the plating solution is lost during the plating operation. KCN and NaCN are added.

The reagent added for correction may be in a solution state or a powder state, but the solution state is advantageous in that the replenishing amount can be easily controlled. In that case, it can be added as a high-concentration correction solution in order to perform replenishment efficiently. In order to add the plating film component as a high-concentration correction liquid, a heating means such as a heater is provided in the correction liquid storage tank liquid.

Hereinafter, the case of controlling the plating film component concentration will be described in more detail with reference to FIG.

The device of the present invention is operated so as to be activated at predetermined time intervals. At the set time,
In accordance with a command from the control device (D), the plating solution 2 is collected from the plating tank 1 via the line A1, and the sample liquid storage tank A2
Sent to Further, the plating solution is sent to three measuring tanks, and water or a reagent is supplied from each tank to each of the tanks, and after performing necessary processing, the characteristic values of the plating film component concentration, free cyanide concentration, and pH are measured. Is done.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the case of controlling the concentration of a plating film component will be described in more detail with reference to FIG.

The sample solution collecting means (A) collects the plating solution 2 from the plating tank 1. A line A1 for transferring a sample in the plating tank 1 and a sample liquid storage tank A2 for temporarily storing the sample;
And an electromagnetic metering pump A3 for supplying the sample solution from the plating tank 1 to the storage tank A2, a line A4 for further transferring the sample solution to the measuring device (B), and an electromagnetic valve A5 provided on the line.
It is composed of In this example, there is further provided a pump A6 and a line A7 for returning excess sample liquid remaining in the sample liquid storage tank A2 to the plating tank 1. Valves A8 and A9 provided on line A1 and valves A10 and A provided on line A7
11 is normally open. Also, the valves Al2 and A13 provided on the line A4 are normally open.

The plating film component concentration measuring device (B) comprises a plating film component concentration measuring tank B1, an electrode B2 which can be inserted into and pulled up from a sample solution in the measuring tank B1, and a stirring device B3.
And a heater B4 for decomposing the cyan compound, and a cooling pipe B for cooling the sample liquid decomposed by the cyan compound
5 and a thermocouple B6 for measuring the temperature of the sample liquid.
A line B7 for discharging the sample liquid after the measurement and a cleaning liquid described later from the measurement tank B1, and a pump B8
And a waste liquid tank B9 for storing the discharged liquid.

The measuring means (B) includes a pure water tank B10 for storing pure water, an acid tank B11, and a buffer (pH 4).
8) A tank B12 is provided, and a measuring tank B is provided from each tank.
1. Lines B16, B17 and B18 respectively provided with electromagnetic metering pumps B13, B14 and B15 extend to 1. The valves shown in each line are normally open.

The correction reagent replenishing means (E) includes a replenishing solution tank E2 containing a correction solution (cyanide compound solution) E1 for a plating film component, a heater E3, a thermocouple E4, a level sensor E5, and E1. A line E6 for supplying to the pump and an electromagnetic metering pump E7. The electromagnetic metering pump E7 is controlled by the control device (D). Valves E8 and E9 provided on line E6 are normally open.

In FIG. 2, the components of the plating film are corrected by replenishing the solution of the components. However, if the material to be replenished is suitable for replenishing with powder, an apparatus for replenishing in the powder state is used. Can be exchanged.

The automatic control of the plating film component concentration using the apparatus shown in FIG. 2 is performed as follows.

The device of the present invention starts operating at a predetermined time interval set in advance. At the set time, the electromagnetic metering pump A3 is actuated by the command of the control device (D) to collect a predetermined amount of the plating liquid to be measured from the plating tank in operation and transfer it to the sample liquid storage tank A2. Store on Shidan. Next, the electromagnetic metering pump A5 operates to supply a predetermined amount of the sample liquid in the sample liquid storage tank A2 to the plating film component concentration measurement tank B1. When the management of the pH and the management of the free cyanide concentration are performed simultaneously, they are also supplied to the respective measuring tanks (not shown in FIG. 2; see FIG. 3) by the electromagnetic metering pumps A14 and A15. When the supply of sample liquid to each measuring tank is completed,
The pump A6 operates to return the sample liquid remaining in the sample liquid storage tank A2 to the plating tank 1.

The automatic control of the plating film component concentration proceeds as follows.

(1) A predetermined amount of a mixture of sulfuric acid and nitric acid is supplied from the fermentation tank B11 to the plating film component concentration measuring tank B1 to which the sample solution has been supplied by the electromagnetic metering pump B14 in order to decompose the cyanide. .

(2) The sample liquid in the measuring tank B1 is heated by the heater B4, and the cyan compound is decomposed to generate free cyan. The heating is usually at 80 to 200 ° C for 1 to 20 minutes, preferably at 100 to 150 ° C for 3 to 10 minutes.

(3) When the decomposition is completed, the power supply to the heater is stopped, cooling water is supplied to the cooling pipe B5, and the liquid in the measuring tank B1 is cooled to room temperature.

(4) The buffer solution (pH 4 to 8) is supplied from the buffer solution tank B12 to the measuring tank B by the electromagnetic metering pump B15.
1 is supplied.

(5) The electrode B6 is inserted into the solution in the measuring tank B1, and the plating film component concentration is measured.

(6) The measured values are sent to the arithmetic unit (C) and input as shown in the flow chart of FIG. The data is output to a display or a printer as needed.

(7) The measured value is compared with the set value in the arithmetic unit (C). If the measured value is within the set value range, no correction is necessary, and the process ends. However, when the measured value is outside the range of the set value, the correction data is calculated.

More specifically, since the plating film component concentration decreases as the plating operation progresses, it is conceivable to manage the concentration so that it does not fall below a certain lower limit in practical use. In this case, the lower limit value (Xmin) is set as a control index, and the process ends if the measured value (X) is higher than Xmin. When X is equal to or smaller than Xmin, correction data according to the difference (Xo-X) between the target value Xo and the measured value X is calculated. That is, considering the concentration of the plating solution in the plating tank (a constant since it is controlled to be constant) and the concentration (constant) of the replenishing solution E1 described below, the concentration of the coating film component of the plating solution is represented by Xo-Xo. Calculate the volume (correction data) of the replenisher E1 necessary to increase the replenishment. The correction data is output to the control device (D).

(8) The control device (D) activates the electromagnetic metering pump E7 based on the correction data, and
Is supplied to the plating tank 1 in an amount necessary for correction. In this manner, the necessary steps are completed, but it is desirable that the next step be performed.

(9) The amount of the replenisher is sent to the control device (D) and recorded in a storage device (not shown).

(10) The liquid in the measuring tank B1 whose measurement has been completed is sent to the waste liquid tank B9 by the pump B8.

(11) The electromagnetic metering pump B13 is operated to supply a predetermined amount of pure water from the pure water tank B10 to the measuring tank B1, and the inside of the measuring tank B1 and the electrode B2 are washed.

(12) After the cleaning is completed, the cleaning liquid is supplied to the pump B8.
To the waste liquid tank B9.

(13) The electrode B2 is pulled out of the measuring tank B1 and returned to a predetermined position. The automatic control of the pH of the sample solution and the automatic control of the free cyanide concentration are performed in the same manner as described above, except that the specific constitutions of the measuring means and the replenishing means are somewhat different as described below.

In the automatic pH control, as shown in FIG. 3, (a) a sample solution is supplied to a pH measuring tank B19 via a line A17, and the electromagnetic measurement pump B2 is supplied from a pure water tank B10.
0, a predetermined amount of pure water used for dilution is supplied through line B21.

(B) The electrode B22 is inserted into the diluted plating solution, and the pH is measured.

(C) As the correction solution to be replenished, an aqueous solution of KOH, NaOH or an acid is used depending on the type of the plating solution as described above. No heating means is required for this replenisher tank.

In the case of strike plating of silver or copper, the pH is required to be 10 or more. Therefore, the lower limit may be set and managed, so that it is similar to the management of the plating film component concentration. In the case of partial plating of silver, since the pH generally rises, a practical upper limit may be set and managed so as not to exceed the upper limit. Except for setting the upper limit value instead of the above Xmin, the same as the management of the plating film component concentration may be used.

In the automatic control of the free cyan concentration, as shown in FIG. 3, (a) from the buffer solution tank B24 to the electromagnetic metering pump B25, the free cyan concentration measuring tank B23 to which the sample solution was supplied via the line A16. , Line B26, 1 M NaO
A predetermined amount of the H aqueous solution is supplied and diluted.

(B) If necessary, a predetermined amount of pure water used for dilution is supplied from a pure water tank B10 by an electromagnetic metering pump B27 and a line B28.

(C) The electrode B29 is inserted into the liquid in the measuring tank B23, and the free cyan concentration is measured.

(D) The controller (D) replenishes the correction liquid based on the calculated correction data, and an aqueous solution of KCN or NaCN is used as the correction liquid. No heating means is required for this replenisher tank.

Since the amount of free cyan may decrease during the plating operation, a constant lower limit may be set and managed in the same manner as the plating film component concentration.

[0061]

According to the automatic plating liquid management apparatus of the present invention, the concentration of plating film components in the plating liquid during various plating operations including partial silver plating, silver strike plating, and copper strike plating. , Free cyanide concentration and pH can be managed automatically without the need for manual intervention. Therefore, the composition of the plating solution is always maintained in a predetermined range, and the quality of the obtained plating film is always maintained in a favorable range.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a plating solution automatic management device of the present invention.

FIG. 2 is a diagram schematically showing a configuration in the case of controlling a plating film component concentration in the automatic plating solution management apparatus of the present invention.

FIG. 3 shows the pH of the automatic plating solution management apparatus of the present invention.
FIG. 3 is a diagram schematically illustrating a configuration of a measurement stage for measuring a free cyan concentration.

FIG. 4 is a flowchart showing a procedure for controlling the plating film component concentration by the method of the present invention.

[Explanation of symbols]

 (A) Sample liquid sampling means (B) Characteristic value measurement means (C) Calculation means (D) Control means (E) Correction reagent replenishment means Electrode for electrode B4 Heater B5 Cooling pipe B13 Electromagnetic metering pump B14 Electromagnetic metering pump B15 Electromagnetic metering pump E1 Correction solution E2 Replenisher tank E3 Heater E7 Electromagnetic metering pump

Claims (4)

[Claims] An automatic plating solution management method for automatically replenishing a correction reagent for managing a characteristic value of a plating solution in a plating tank in which a plating operation is performed so as to be maintained at a target value. Taking a sample solution for measurement from the plating solution at regular time intervals; measuring the characteristic values of the sample solution; comparing the obtained measured value with a preset target value; If the measured value is within the range of the set value, the process is terminated. (Ii) If the measured value is outside the range of the set value, the correction data is calculated; A method for automatically managing a plating solution, comprising a step of replenishing a correction reagent so that the characteristic value of the plating solution becomes a set value. 2. The plating solution according to claim 1, wherein the plating solution is a plating solution for partial plating of silver, silver or copper strike plating, and the characteristic value to be managed is one or more of a plating film component concentration, a free cyanide concentration, and a pH. 2. The automatic management method according to claim 1, wherein the number is two or more. 3. An automatic plating solution management apparatus for automatically replenishing a correction reagent for managing a characteristic value of a plating solution in a plating tank in which a plating operation is performed so as to be maintained at a target value. Means for collecting a sample liquid for measurement from the plating tank (A)
Means for measuring the characteristic value of the sample liquid (B)
And; comparing the obtained measured value with a preset target value;
Means (C) for calculating correction data when the measured value is out of the range of the set value; according to the correction data obtained by the calculation means so that the characteristic value of the plating solution becomes the set value. Control means (D) for controlling the next replenishing means (E) to adjust the replenishment amount of the replenishing correction reagent; and means (E) for replenishing the correction reagent to the plating solution in the plating tank. Automatic management system for plating liquid. 4. The plating solution according to claim 1, wherein the plating solution is a plating solution for partial plating of silver, silver or copper strike plating, and the controlled characteristic value is one of a plating film component concentration, a free cyanide concentration, and a pH. The automatic management device according to claim 3, wherein the number is two or more.