Method and an apparatus for detecting concentration of a chemical treating solution and an automatic control apparatus thereof

• US 5,450,870 A
• Filed: 12/16/1993
• Issued: 09/19/1995
• Est. Priority Date: 04/17/1992
• Status: Expired due to Fees

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Niwa, Masashi, Kondo, Koji, Kojima, Fumio, Suga, Makoto, Ishida, Nobumasa
• Primary Examiner(s): Hepperle, Stephen M.
• Application Number:
  US08/162,187
• Time in Patent Office: 642 Days
• Field of Search: 137/3, 137/93
• US Class Current: 137/3
• CPC Class Codes: C23C 18/1628 Specific elements or parts of the apparatus
• CPC Class Codes: C23C 18/1683 Control of electrolyte composition, e.g. measurement, adjustment regeneration of bath C23C18/1617
• CPC Class Codes: G05D 21/02 characterised by the use of electric means
• CPC Class Codes: Y10T 137/0329 Mixing of plural fluids of diverse characteristics or conditions
• CPC Class Codes: Y10T 137/2509 By optical or chemical property

Abstract

According to the present invention, the changing rate of the predetermined component concentration is determined, based on the difference between the predetermined component concentration in a chemical treating solution (a plating solution) which is analyzed this time and the predetermined component concentration analyzed last time, both measured by an analytical means, and the difference of each sampling time for analysis of each component concentration by the analytical means (140). Subsequently, the correction amount for the analyzed result of this time based on the changing rate obtained above and the elapsed time from the sampling point of time of the plating solution of this time for analysis of the plating solution by the analytical means to the current point of time (150), and then the analyzed result is corrected based on the resulting correction amount to compute or calculate the current concentration (160). As the result, the current concentration can be detected accurately regardless of the analyzing time of the plating solution by the analytical means.

Claims

1. A concentration detection method for detecting the concentration of a predetermined component in a chemical treating solution, the method comprising the steps of:

sampling the chemical treating solution at a first time to obtain a first sampled solution, and analyzing, in a first analysis, the first sampled solution for first concentration information corresponding to a first concentration of the predetermined component in the chemical treating solution at the first time, and

sampling the chemical treating solution at a second time when a predetermined time has elapsed from the first time to obtain a second sampled solution, and analyzing, in a second analysis, the second sampled solution for second concentration information corresponding to a second concentration of said predetermined component at the second of time; and

calculating a third concentration of the predetermined component in the chemical treating solution after another predetermined time has elapsed from the second time, said calculating being based on the first and second concentration information and on the times required for said first analysis and said second analysis.

2. The concentration detection method according to claim 1, wherein the third concentration is a concentration of the predetermined component in the chemical treating solution at the time when the time required for obtaining said second concentration information has elapsed from said second time.

3. A concentration detection apparatus for detecting the concentration of a predetermined component in a chemical treating solution, the apparatus comprising:

analytical means in which the chemical treating solution is sampled, and in which the sampled solution is analyzed in a first analysis to obtain first concentration information corresponding to a first concentration of the predetermined component in the chemical treating solution at a first analyzing time and is analyzed in a second analysis to obtain second concentration information corresponding to a second concentration of said predetermined component at a second analyzing time when a predetermined time has elapsed from the first analyzing time;

concentration calculating means for calculating a third concentration of the predetermined component in the chemical treating solution when another predetermined time has elapsed from the second analyzing time, said third concentration being based on the first and second concentration information and on the time required for said first analysis and said second analysis.

4. The concentration detection apparatus according to claim 3, wherein the third concentration of said predetermined component is a concentration at the time when the time required for obtaining said second concentration information has elapsed from said second analyzing time.

5. A concentration detection apparatus for detecting the concentration of a predetermined component in a chemical treating solution, the apparatus comprising:

analytical means for sampling the chemical treating solution periodically, and for subsequently analyzing the predetermined component concentration in the chemical treating solution;

changing rate calculating means for calculating a changing rate of said predetermined component concentration in the chemical treating solution, based on;

a difference between a first concentration of said predetermined component and a second concentration of said predetermined component, said second concentration being measured at a predetermined time after measurement of said first concentration and on

a time difference between a time required for sampling of said chemical treating solution to obtain said first concentration and a time required for sampling of said chemical treating solution to obtain said second concentration;

changing amount calculating means for calculating a third concentration at a third predetermined time, said third concentration being based on the changing rate calculated by the changing rate calculating means and on a time difference between said second predetermined time and the third predetermined time when a predetermined time has elapsed since said second predetermined time; and

correcting means for outputting at said third predetermined time the third concentration result calculated by the changing amount calculating means into said chemical treating solution as said predetermined component concentration.

6. An automatic control apparatus for a chemical treating solution, the apparatus comprising:

analytical means for sampling the chemical treating solution periodically, and for subsequently analyzing a predetermined component concentration in the chemical treating solution;

changing rate calculating means for calculating a changing rate of said predetermined component concentration in the chemical treating solution, based on;

the difference between a first concentration of said predetermined component and a second concentration of said predetermined component, said second concentration being measured at a predetermined time after said first concentration and on

a time difference between a first time required for sampling of said chemical treating solution to obtain said first concentration and a second time required for sampling of said chemical treating solution to obtain said second concentration;

changing amount calculating means for calculating a third concentration at a third predetermined time, based on the changing rate calculated by the changing rate calculating means and on a time difference between said second predetermined time and the third predetermined time when a predetermined time has elapsed since said second predetermined time;

correcting means for outputting the third concentration result calculated by the changing amount calculating means into said chemical treating solution as said predetermined component concentration;

concentration detection means for detecting the second concentration information of the predetermined component consumed by chemical treatment in the chemical treating solution contained in a chemical treatment vessel;

supply means for supplying the predetermined component based on its detected concentration by the concentration detection means into the chemical treating vessel as a replenisher;

control amount calculating means for calculating a supply rate or a supply amount of the replenisher by said supply means, based on the second concentration of said predetermined component calculated by said changing amount calculating means and said third concentration of said predetermined component calculated by said changing amount calculating means; and

supply control means for controlling driving of said supply means depending on the supply rate or supply amount calculated by the control amount calculating means.

7. A concentration detection method for detecting the concentration of a predetermined component in a chemical treating solution, the method comprising the steps of:

detecting first concentration information corresponding to a first concentration of the predetermined component in the chemical treating solution at a first analyzing time and second concentration information corresponding to a second concentration of said predetermined component in the chemical treating solution at a second analyzing time where a predetermined time has elapsed from said first analyzing time;

memorizing a plurality of rules based on said first concentration information and on said second concentration information and a plurality of functions partitioning said first concentration information and said second concentration information in said plurality of rules into sets having predetermined ranges and also setting certainty factors in the partitioned sets, and then operating each certainty factor in said plurality of rules; and

setting a command value in a third concentration of said predetermined component in said chemical treating solution from the certainty factors, and then supplying said predetermined component to said chemical treating solution according to the command value of said third concentration.

8. The concentration detection method according to claim 7, wherein the plurality of rules comprises a plurality of concentration information of the predetermined component, including pluralities of first and second concentration information, said pluralities of first concentration information and second concentration information in said plurality of rules being partitioned into sets having predetermined ranges, and wherein the functions set with the certainty factors in the partitioned sets are memorized.

9. A concentration detection apparatus for detecting the concentration of a predetermined component in a chemical treating solution, said apparatus comprising:

analytical means for detecting first concentration information corresponding to a first concentration of the predetermined component in the chemical treating solution at a first analyzing time and second concentration information corresponding to a second concentration of said predetermined component in the chemical treating solution at a second analyzing time where a predetermined time has elapsed from said first analyzing time;

memory means for memorizing

a plurality of rules set based on said first concentration information and on said second concentration information and

functions partitioning said first concentration information and said second concentration information in said plurality of rules into sets having predetermined ranges and also setting certainty factors in the partitioned sets; and

setting means for operating each certainty factor in said plurality of rules, and then setting the command value in concentration of said predetermined component in said chemical treating solution from the certainty factors.

10. The concentration detection apparatus according to claim 9,

wherein the plurality of rules memorized in said memory means comprise plural concentration information of the predetermined component, and

wherein said memory means memorizes said rules and functions set with the certainty factors in the sets having predetermined ranges into which said plural first concentration information and second concentration information are partitioned.

11. An automatic control apparatus for a chemical treating solution for use in a chemical treatment, the apparatus comprising:

supply means for supplying each component consumable by the chemical treatment in the chemical treating solution consisting of a plurality of components as a replenisher into a chemical treatment vessel containing the chemical treating solution;

condition input means for memorizing a command concentration of said replenisher in said chemical treating solution and chemical treatment conditions of material to be chemically treated;

control amount calculating means for calculating a supply rate or a supply amount of said replenisher to be supplied by said supply means based on the command concentration of each replenisher in the chemical treating solution and the chemical treatment conditions of the material to be chemically treated, both memorized in the condition input means;

supply control means for controlling the supply rate or the supply amount of each replenisher from said supply means into said chemical treatment vessel, depending on the supply rate or the supply amount calculated by the control amount calculating means;

concentration analyzing means for analyzing each replenisher in said chemical treating solution independently;

concentration changing amount calculating means for calculating a changing amount per unit time of concentration of each replenisher based on the analyzed result by the concentration analyzing means;

memory means for memorizing a plurality of rules set based on deviations between the concentration of each replenisher analyzed in said concentration analyzing means and the command concentration, the changing amount of each replenisher concentration calculated by said concentration changing amount calculating means and the correction amount of the supply rate or the supply amount of each replenisher, and functions partitioning the deviations of each replenisher concentration from the command concentration analyzed by said concentration analyzing means in said plurality of rules, the changing amount of the each replenisher concentration calculated in said concentration changing amount calculating means and the correction amount of the supply rate or the supply amount of each replenisher into sets having predetermined ranges and setting certainty factors in partitioned sets;

correction amount calculating means for operating each certainty factor in said plurality of rules and for calculating the supply rate or the supply amount of each replenisher from the resulting certainty factor; and

control amount update means for correcting the supply rate or the supply amount calculated by said control amount calculating means based on the correction amount calculated by said correction amount calculating means, to change the supply rate or the supply amount of each replenisher controlled by said supply control means.