JPS602386B2 - How to manage plating solution and chemical solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for managing a plating solution and a chemical solution used for pre-treatment or post-treatment of plating (hereinafter, the above two types of solutions are referred to as chemical treatment solutions), and in particular determines the properties of the solution. It concerns methods of managing physical and chemical quantities.

In order to achieve more uniform and economical treatment with a chemical treatment liquid, it is required to strictly control physical and chemical quantities such as temperature, concentration, and viscosity of the treatment liquid.

For example, printed circuit boards, which are made by plating a thin metal film on an insulating board, are required to meet the demands of mechanical strength and uniformity of film thickness as electronics progresses. To achieve this, it is necessary to adjust the concentrations of various components in the plating solution appropriately and uniformly.

By the way, to explain the control and adjustment method of the secondary chemical processing solution for the above-mentioned plating solution, for example, for a certain period of time (for example, 3
The various concentrations were manually measured at intervals (time), and based on the results, the appropriate amount was replenished each time, for example, until the concentration was 10% higher than the set value, but this method As shown in Figure 1, the concentration varies greatly, and there is a time delay before the concentration becomes uniform.
It did not comply with the above request.

Furthermore, in order to solve the above-mentioned time delay problem and ensure the stability of the liquid using this conventional method, a large-scale rope system was required, which resulted in an increase in the cost of the product. . Furthermore, as a method different from the above, the second
As shown in the figure, the concentration of each component of the plating solution is continuously analyzed, and when the resulting concentration is lower than the lower limit of the set value with a range, the supply voltage is automatically switched off. A method was also used in which the polishing groove device was activated to increase the concentration, and when the concentration exceeded a set upper limit, the operation of the polishing groove device was automatically stopped.

However, although this method performs analysis continuously,
Because the replenishment is intermittent, the problem of concentration variations and the time delay until it becomes uniform is not solved, as in the case of manual analysis mentioned above, and it is not possible to keep the concentration constant continuously. However, when an electrode is used as a concentration sensor, the accuracy of analysis decreases over time due to the influence of deposits on the electrode during measurement, resulting in a disadvantage that the variation in concentration increases accordingly. This invention has been proposed in view of the above-mentioned circumstances, and it supplies the physical and chemical measurement values of plating solution and other chemical treatment solutions while maintaining a balance with the amount of the solution used. By,
The purpose is to manage and coordinate.

This invention includes the steps of: measuring and detecting a physical quantity or chemical quantity indicating the state of the liquid to be managed at regular intervals; calculating a proportional replenishment amount from the difference between a reference setting value and the currently measured value; It consists of a step of calculating a fixed replenishment amount using the value, the previous measured value, and the previous proportional replenishment amount, and a step of replenishing the controlled liquid with the fixed replenishment amount and proportional replenishment amount determined as above. This is the main feature, and will be explained in more detail below.

*FIG. 3 is a flowchart showing the general application of this invention.

In Fig. 3, the liquid to be managed contained in the treatment tank 1 is sampled at regular intervals (for example, 1 hour) and physical quantities such as temperature, viscosity, concentration, specific gravity, solution (hydrogen ion concentration), etc. Or the stoichiometry is measured. The measurement results are taken out as electrical quantities and input to the CPU 2, and the CPU 2 calculates the proportional replenishment amount and fixed replenishment amount in the following manner. The proportional replenishment amount is the amount of liquid, heat, etc. that is temporarily or constantly replenished into the processing liquid tank 1 in order to correct the deviation from the standard set value. It is calculated, but basically the proportional supply amount (Do) = (standard setting value - current measured value) x pot capacity ......
・・・It is determined by m■.

Since this value is the amount of replenishment per unit time when replenishment is continued at all times, the amount of replenishment per unit time when replenishment is attempted in a time shorter than the sampling interval (see Figure 4) is D=D.

X sampling interval time, . ．． 、． ．． 、． ．． ．． ．． 、． ．．
[2-It's time for replenishment.

The fixed amount of replenishment is the amount of liquid or heat that is constantly replenished into the processing liquid tank 1 in order to balance the load of the liquid, and is calculated from various factors, but basically the fixed amount of replenishment is 2 (current measured value - previous measured value) x tank capacity ÷ 10th previous proportional replenishment amount [(D.

) or (D)]. (3) The amount of replenishment per unit time is determined by the sampling interval time.

When the correct amount of quantitative replenishment is performed, the desired physical or chemical quantity of the liquid is kept constant in the chemical processing liquid. Depending on the object to be measured, for example, the accuracy of the sensor used when measuring concentration may not be sufficient. In this case, more accurate quantification can be achieved by averaging the amount of quantitative replenishment calculated multiple times using the above glue formula. Replenishment amount can be determined.

The sum of the proportional replenishment amount and fixed replenishment amount determined as above is replenished into the processing liquid tank 1 as shown in equation (2), and the deviation from the standard setting value is corrected by the proportional replenishment. , the balance with the load will be maintained by constant replenishment.

Total supply amount (per hour) = Proportional supply amount [(Do) or (D
)] Ten quantity supply amount (H) ・・・・・・・・・・・・・
...'4} Furthermore, experimentally, better results are obtained by performing proportional replenishment at about one-fifth of the sampling interval according to formula {2) than by constantly replenishing it in addition to quantitative replenishment. (See Examples below).

Figure 4 shows the state of actual management of chemical treatment liquids over time based on the above explanation, and Figure 4a shows changes in physical quantities and chemical quantities over time. Fourth
Figure b shows the change in the amount of replenishment over time.

In FIG. 4b, the chemical treatment liquid is initially replenished in an amount Ho calculated theoretically before it is managed according to the present invention. However, this initial expected supply amount Ho may be zero. Next, at time t, the first sampling is performed to measure the physical quantity or chemical quantity that is the subject of management, and [the first proportional supply amount calculated based on formula 11 and formula D, is replenished in a time approximately a fraction of the sampling interval.

Therefore, when the proportional replenishment is completed, the adjusted amount becomes approximately the reference setting value. A second sampling is performed after a certain period of time, for example, one hour after time t, and the proportional replenishment amount D2 is calculated in the same way as the previous time, and proportional replenishment is performed based on the calculated amount D2. At this time, furthermore, using the first sampling result (previous measurement value), the second sampling result (current measurement value), and the first proportional supply amount D, [based on formula 31, Z quantitative The replenishment amount date,' is calculated, and the result is stored in the storage device. Furthermore, the third sampling is performed at time t3, which is a certain period of time after time t2, and it goes without saying that the proportional replenishment amount D3 is calculated and the proportional replenishment is performed in the same way as the previous time and the time before the previous time. Also, the fixed amount of replenishment is calculated using the rigid formula.For example, sensors used for concentration measurement etc. have some drawbacks in terms of accuracy and reliability, so when calculating the fixed amount of replenishment, It is preferable to take the average of multiple pieces of data.

Therefore, in the example shown in Fig. 4, the fixed amount replenishment date calculated last time at time t, '' and the currently calculated fixed amount replenishment date at time t3,'' are averaged to determine the fixed amount replenishment date as accurate as possible.
is being calculated. However, it is also possible to take the average of the calculated values more times, or if the sensor is expected to have sufficient accuracy, the calculated value only once can be used. The quantitative replenishment amount day calculated in this way is generally a different value from the above-mentioned expected replenishment amount Ho, in which case ΔH=day, one day.

……………【51 theoretical supply amount Ho
It is only necessary to replenish in addition to the proportional replenishment amount D3 at time t3. From then on, time t4, t5...
. . . Sampling continues, the proportional replenishment amount and fixed replenishment amount are calculated, and the replenishment amount is adjusted repeatedly.

At the time t3, if the △day in formula '5' is too large and the sum of the quantitative replenishment amount day and the proportional replenishment amount D3 becomes too large than the standard setting value, then the equation will be changed as shown by the broken line in Figure 4. It may be divided into 2 to 3 times and gradually increased.

Physical quantities that can be managed and adjusted using the methods described above,
Chemical quantities are diverse and include all values that can be extracted as electrical quantities using sensors, such as concentration, base (hydrogen ion concentration), temperature, viscosity, and specific gravity.

Table 1 lists target items that can be managed by applying this invention. Table 2 shows the range of concentration fluctuations as shown in Figure 1 above when the above-described control method for chemical treatment liquid is applied to the concentration control of various components in electroless steel plating solution at a printed circuit board factory. This is a comparison with the results of manual analysis shown in
It can be seen that both the CHO concentration was significantly improved.

Furthermore, Table 3 examines the amounts of various replenishment fluids used under the same conditions as in Table 2, and it can be seen that the number of replenishers themselves has decreased significantly compared to the case of manual analysis.

Table 4 compares the range of concentration changes of various components when this invention is applied to gold plating with conventional control values, and it can be seen that each is significantly improved.

FIG. 5 shows an example of an apparatus for carrying out the invention.

1 is a tank for chemical processing liquid such as plating liquid, and 21 is a sampling pump which pumps up sampling liquid at regular intervals according to instructions from a computer 3, which will be described later.

22 is a sensor; for example, in the case of electroless steel plating, a glass electrode or other potential difference measuring electrode [spotted] is used.
Measurement of hydrogen ion concentration), steel ion concentration, formalin (reducing agent), etc.] Use an absorbance cell (measurement of copper ion concentration).

23 contains various metal ions (e.g. steel ions, gold ions, nickel ions, tin ions), additives (e.g. cyanide,
ammonia), reducing agents (for example, formalin, subphosphoric acid), etc., and 24 is a scale liquid tank for sampling liquid.

Reference numeral 3 denotes a microcomputer, which includes a memory 31 for storing items necessary for program operation such as reference concentration setting values, a comparator means 32 for comparing the output of the sensor 22 and the setting value, and proportional and continuous replenishment amounts. etc., an output means 35 that receives the output of the calculation means 33 and drives the replenishment pump 4, a display 34 for displaying input items and calculation results, and an input means 36 such as a numeric keypad.

Furthermore, 4 is a replenishment pump and 5 is a replenishment tank. In this configuration, the sensor 22 transmits a controlled value, such as concentration, of the sampling liquid to the computer 3 as an electrical signal.
The comparator means 32 compares it with the set value, and the calculation means 33 calculates the proportional replenishment amount and continuous replenishment amount, and the output means 3
At the same time as the replenishment pump 4 is driven in step 5, necessary information is displayed on the display 34. As explained above, in this invention, the plating solution and the chemical processing solution such as chemical solution used for plating pre-treatment or post-treatment are replenished as a sum of proportional replenishment and quantitative replenishment. Adjusting the deviation from the reference value (proportional replenishment) and adjusting the balance with the load (quantitative replenishment) are easy and quick, and if you perform proportional replenishment several times at the beginning of management, it will be easier to adjust the balance with the load (proportional replenishment). As long as there are no fluctuations, the controlled value can be kept constant just by quantitative replenishment, and it has the effect that there is no problem of time delay until the concentration etc. become uniform.

Table 1 Scope of application of this invention, controlled components Table 2 Concentration changes of various components of electroless steel plating solution Plating conditions,
PH 12.4o Mitsuki Yutaka composition
.

Capacity 1.000 Sokame method.
2-7 skin. Yu load 2 skin 8.20 Ta'do 3
5 Table 3 Replenishment amount of various components of electroless steel plating solution (per unit area)
1 liquid... Sulfuric acid steel + formalin
N solution... Caustic soda solution... Alkali + Rochelle salt Plating conditions are 2
Same liquid as shown in the table... Formalin 4th table Changes in various components of gold plating Plating conditions Plating pot 1300 Circulating flow rate 5 revolutions/hour Temperature distribution 320 ± 0. Chi0 Plate ratio 5:1 Distance between poles 5

[Brief explanation of the drawings] Fig. 1 shows the concentration changes (a) and the amount of replenishment (b) of the chemical treatment liquid management method by manual analysis of the subordinate, and Fig. 2 shows the conventional method of managing the chemical treatment liquid. Continuous analysis automatically turns on/off the supply device.
Concentration change (a in the same figure) and supply amount (
Figure b) is shown. Figure 3 is a flowchart showing the general customer experience of this invention, and Figure 4 is a flowchart showing the changes in managed values according to this invention (a
) and the replenishment amount (b in the same figure).Furthermore, FIG. 5 shows an apparatus for carrying out the present invention. Figure 1 Figure 2 Figure 4 Figure 3 Figure 5

Claims (1)

[Scope of Claims] 1. A method for managing a plating solution and a chemical solution, characterized by comprising the following steps. (i) Step of sampling the liquid to be controlled at regular intervals and measuring the physical quantity or chemical quantity that determines the properties of the liquid to be controlled. (ii) Based on the difference between the standard setting value and the current measured value. , step of calculating the proportional replenishment amount (iii) step of calculating the fixed replenishment amount from the current measured value, the previous measured value, and the previous proportional replenishment amount (iv) the proportional replenishment amount calculated in steps (ii) and (iii) above. Step 2 of replenishing the replenishment amount and quantitative replenishment amount to the liquid to be managed. Claim 1, characterized in that the liquid to be managed is used that has been replenished as expected by the amount of decrease that can be calculated theoretically. Management method of plating solution and chemical solution described in . 3. The method for managing plating liquids and chemical liquids as set forth in claim 1, wherein the average of a plurality of quantitative replenishment amounts calculated for each sampling is taken as the actual quantitative replenishment amount. 4. The method for managing plating liquids and chemical conversion liquids according to claim 1, wherein the proportional replenishment time is shorter than the sampling interval time.