KR20010052287A - Chemical mixing, replenishment, and waste management system - Google Patents

Abstract

Chemical control systems for controlling the chemistry of a chemical solution having a predetermined chemical component in a plating system, such as a NiFe plating system, use a mixing container for containing a plating liquid and a holding container for containing a plating liquid delivered from the mixing container. The precise delivery batch delivers the correct predetermined amount of the predetermined component of the plating liquid to the plurality of mixing containers and the holding container. Transfer of the plating liquid between the mixing and holding containers is performed by a delivery pump. Nitrogen gas humidified with deionized water prevents the plating liquid from acquiring or dewatering the water, and the humidified nitrogen gas is humidified to a predetermined relative humidity relative to the temperature of the plating liquid in the mixing container. This process is accomplished by forcing nitrogen gas through a column at the same temperature as the plating solution. Precise delivery of chemical components is achieved by air pumps arranged in series with orifices and inexpensive flowmeters. The air pump is a double displacement double diaphragm pump.

Description

Chemical Mixing, Replenishment, and Waste Management Systems {CHEMICAL MIXING, REPLENISHMENT, AND WASTE MANAGEMENT SYSTEM}

Chemical management systems such as plating process control systems are required to perform a number of functions, but not all of them have been successfully performed in the prior art. For example, in chemical systems using NiFe plating baths, it is necessary to make the NiFe plating baths available at any time when needed. The system for managing the bath should preferably manufacture and maintain a new bath, assess the bath chemistry and control it. The temperature of the bath must be controlled and the amount of fluid in the bath must be replenished as evaporation occurs. In addition, it is desirable to perform dummy plating to age the jaw.

In the production environment, it is necessary to distribute the plating liquid to the tank in the production area. Particles are filtered and continuous flow of the solution must be carried out in the connecting pipe.

In some manufacturing environments, a plurality of holding and mixing tanks are provided at predetermined locations in the manufacturing area. In some cases, each set of mixing and holding tanks has their respective chemical properties. There is a need for arrangements that reduce redundant components in chemical control systems that control the operation of these multiple tank areas.

As described above, each of these areas may be provided with a holding tank and a mixing tank. The holding tank stores the plating liquid in a state where it can be used immediately. Meanwhile, the mixing tank is used for dummy plating by preparing a plating solution. Of course, each of these tanks is made to be chemically inert in terms of the chemical properties of the plating liquid. Materials known to be suitable for this purpose are Teflon ^R materials and equivalents.

In addition, a chemical control system is needed to allow nitrogen gas to fill the space above the liquid surface in the tank. Nitrogen gas forms a blanket that prevents oxidation of chemicals and, when properly humidified, increases the amount of solution due to known fog humidifiers. In addition, a suitably humidified nitrogen blanket reduces the dehydration of the plating liquid, thereby increasing its concentration.

Many system parameters must be monitored and controlled. These include the individual concentrations of Ni and Fe, especially in NiFe plating environments. In addition, the pH of the solution and its density and temperature need to be controlled within a predetermined range. In addition, the dummy plating system including the plating schedule and the current used therein must be controlled as well as the Fe concentration during the dummy plating.

In addition to the above, there is a need for a sensor system that provides accurate information about the amount of fluid in the tank. For example, external proximity sensors can be misoperated by certain changes in environmental conditions such as light crystal tank wall buildup or humidity. Sensors used for industrial purposes should not be affected by tank wall build up, foaming, agitation, temperature, humidity, RF interference, or electrical noise. The sensor system should not need to be adjusted after installation. It should also provide continuous measurements along the total depth of the tank. This measurement capability enables immediate inventory of the contents used in other parts of the system, specifically the control software, continuous monitoring of pump performance and verification of flow sensor accuracy.

Summary of the Invention

Purpose of the Invention

It is an object of the present invention to provide a sensor system that provides an accurate indication of the amount of fluid in a tank simply and economically.

It is a further object of the present invention to provide a simple approach to humidifying nitrogen gas to accurately block evaporation or increase of plating liquid in a mixing or holding tank.

It is an object of the present invention to provide filter arrangements for chemicals to be recycled.

It is a further object of the present invention to provide a method for mixing and accurately delivering chemical components in a mixing tank.

It is an object of the present invention to additionally provide a batch for reliably and accurately measuring the pH of a chemical in a tank using a plurality of pH sensors.

It is a further object of the present invention to provide a batch for measuring the fluid content in the tank along the total depth of the tank.

Another object of the present invention is to provide an arrangement for maintaining a circulating fluid at a constant temperature.

Overview of the Invention System

This and other objects are achieved by the present invention in one aspect providing a NiFe blend, analyzer and distribution system. This specific aspect of the invention is designed to achieve the following main objects:

Automated precision blending and mixing of NiFe plating solutions

Automatic solution preparation by mixing, filtration and dummy plating

Automated solution maintenance through temperature control, continuous filtration and chemical analysis, and replenishment

Customer-provided distribution loop (s), chemical feedstock and host computer network connections

Continuous feeding of the NiFe solution prepared by the holding or dispensing tank into the dispensing loop (s). The tank is automatically refilled (depending on level) after a user definable amount of solution is dispensed by the dispensing loop to the plating tool.

Chemically Supported Mixing and Distribution System

The first part of the present system relates to a chemically supported mixing and dispensing system. All operational functions are available from the System Manager.

Blending and Blending

Precision blending is achieved through the use of high accuracy, low maintenance delivery systems and level sensors for the addition of wet chemicals and water. Manual dry chemical addition is aided by operator prompts and instructions and easy access delivery panels. The system is designed to accommodate future expansion and to be renewed in terms of automated dry chemical delivery systems for chemicals such as sodium saccharin, boric acid and the like.

Efficient solution amalgamation is achieved through a combination of variable speed mixing, temperature control (primarily to assist in dissolution of boric acid), and recycling. Continuous level monitoring provides high level of fault and low level of control and alarm. Level monitoring and solution metrology are used together as system diagnostic ports to alert the operator to possible subsystem failures or necessary component correction (s).

Solution manufacturing

Solution preparation involves continuous filtration by recycling through an external heat exchanger. In addition, the mixing tank is equipped with the hardware necessary to cause electrodeposition inside the vessel. The anode and cathode are placed in separate containers from which the solution in the mixing tank is recycled during the dummy plating cycle. Separating the electrode from the solution in the mixing tank avoids further dissociation of the anode which affects solution composition and contamination. In addition, this design facilitates easy removal of the anode and cathode assemblies as needed.

Solution Storage and Distribution

Once the solution preparation and regulation (measuring) is completed in the mixing tank, the system sends the solution to the maintenance / dispensing tank. In the holding tank, the solution is continuously monitored for compositional analysis and temperature. The adjustment is automatically performed by the metrological control system in terms of composition. The temperature is controlled locally in the holding tank, and the metrological control system monitors the temperature and warns and alerts the operator if the temperature deviates beyond the user-defined range. The holding tank is equipped with continuous level monitoring and control. The primary function of level monitoring in the holding tank is (1) high- and low-failure monitoring alarms and functional interlocks, (2) automatic adjustment of replenishment calculations based on actual levels, and (3) solution retention in the mixing tank. It is the signal transmission necessary to carry it to the tank.

The system includes a connection that allows the solution in the holding tank to be dispensed into a "gloval loop" (the global loop supplies the actual plating reservoir) and recycled back to the holding tank. The return point includes a filtration device used to filter out any particles that can be introduced from the global loop.

After the solution is transferred from the mixing tank to the holding tank, blending and preparation of a new batch of NiFe solution begins. The mixing tank and the holding tank function together in such a way that the holding tank is not empty or is overfilled. The solution in the mixing tank will not be sent to the holding tank until all of the pre-programmed routines for proper solution preparation have been completed.

Solution

Critical parameters of the solution are monitored and controlled in combination with automated titration techniques and the introduction of other subsystem elements that directly monitor other items such as pH and specific gravity. Continuous filtration is carried out by recycling the solution through an external heat exchanger designed for heating and cooling conditions. Filter pressures and temperatures are monitored from a system manager as described below. The system manager additionally provides alarms and alarms to the operator for component failure or required maintenance.

Each filter position is equipped with double filtration for automatic switching. When the system detects that one of the filters has differential pressure, it automatically activates the required valve to replace it with a backup filter and alerts the operator that the primary filter needs to be replaced. Once the automatic replacement is complete, the backup filter will be the primary filter and the newly replaced filter will be the backup. This design allows for filter maintenance without shutting down the tool or interrupting the solution supply to the dispense loop.

System manager

In an embodiment of the present invention the system managers are certified Semi S2-93 and 03, and in an embodiment of the present invention provide a host contact protocol to standard ASCII, DDE or 513C5 / GBM (serial or Ethernet). All functions of the blend station and metrological control system, including data delivery, history, maintenance, and reporting, are available from the system manager (IBM PC). The system manager is a computerized control center designed for user convenience. The use of graphical and data display screens allows the operator to connect with the system effectively and with minimal training. The system manager displays and stores process conditions and analysis results and uses the information to initiate alarms, alarms and chemical dispenses, replenishments, cleanups, and calibration routines.

Chemical control system

The chemical control system of the present invention comprises up to four modules in certain embodiments:

Automatic chemical analyzer;

· Auto chemical supplement

Variable I / O interface (LCU) for communication and control of remote electro-mechanical devices and computer-based systems; And

Full process control and PC system processing that connects all modules to the MIS system and provides operator alarms and alarm reporting on a graphical operator interface.

Chemical analyzer

The analyzer is the heart of the system, providing high accuracy in on-line automated chemical analysis. The analyzer is designed to automatically draw samples from multiple process tanks and perform chemical analysis of process chemicals, while sending the results of analysis to a computer processor, which is described below. Self-calibration and diagnostic routines programmed into the analyzer ensure consistent performance and high accuracy in terms of analytical measurements and chemical monitoring.

Chemical supplement

The replenisher receives chemical addition instructions from the system manager based on programmed conditions (actual results versus desired operating range) or responds to manually entered operator commands. The system is designed to conduct a chemical stock inventory and deliver reports on chemical use by the process tank. In certain illustrative aspects of the invention, a keypad is provided for remote operation control.

Local Control Unit-Variable I / O Interface

The local control unit (LCU) monitors physical process parameters such as temperature level, conductivity, pH voltage and the like. The LCU is designed to accept digital or analog signals from local control units. This information is sent to the system manager via a serial link compared to the operator-defined set-point, and logged in a history file. The information is used to provide alarms and alarm conditions and to initiate control functions connected in series with the LCU. The LCU electrically operates certain hardware, such as heating and cooling devices, water solenoids, drain valves, etc., which are intended to be required to perform the necessary adjustments.

Primary automation routine

The primary automation routine of the system of the present invention includes the following operating steps:

1. Power on Starts all components and subsystems and puts them into standby mode.

2. In the Start New Batch Operator command, all settings are checked for valid input user-defined methods of events and initiation.

3.X volume controlled by flow sensor identified by deionized water fill level sensor

4. Operator Prompt Prompt operator (or user-defined manual step (s)

5. Requires confirmation of manual steps to continue operator verification program

6. A chemical blending mixer is started, and chemicals are added via the precision flow sensor identified by level.

7. Chemical mixing solution is mixed for X seconds / minute

8. Confirmation of Mixing Run the stirrer and analyze the Ni, Fe and / or pH twice in the solution. If the verification fails, the test returns to X before the operator activates the alarm.

9. Solution Maintenance Analyze Ni, Fe and / or pH for solution. Replenish the appropriate concentration to bring the solution to specification

10. Same as chemical mixing step 7

11. Same as Mix Check Step 8

12. Dummy Plating (Chemical Analysis and Replenishment Can Be Operated or Paused Individually During Dummy Plating Cycles) Turn the solution to operating temperature, lower the electrode into the solution, and set the current to user-defined amp-minutes. Accreditation

13. Amp-Min Tuning All supplemental chemicals can be added based on assay results and amp-minutes

14. amp-minute tuning When flagged or selected, amp-minute supplementation is automatically adjusted based on analysis results

15. Operator prompt Requires operator permission to open the dispense loop valve.

16. Dispense-on solution is continuously monitored, controlled and aged

17. Distribute Off-Level Low The system goes into standby mode, or initiates a cleanup routine and then goes into standby.

18. Cleanup This routine is user definable. Spray headers and water fill valves, pumps and mixers are set to operate sequentially as part of the cleanup routine

19. Return to Step # 2

The IBM-compatible PC-based system manager of the present invention is a standalone unit that integrates the operation of other components into a fully integrated network. The system provides total control over any chemical process. The system manager records the received information in a database and records the history of each process parameter. The current parameter value is compared with a set set point limit that provides alarms and alarm indications and initiates the automated control function. The module in charge of controlling each parameter activates the necessary control unit to return the parameter to the optimum value.

The system manager provides the operator with a full-featured, menu-driven display of all process information accumulated by the other modules. The operator can access the desired information by selecting the appropriate display screen on the system terminal. In a particular illustrative aspect of the invention, each screen is set with cascading password protection. Graphical display screens are especially

Process status

Parameter status

Parameter history

Parameter set-point

Parameter data accumulation schedule

Parameter Supplementary Information

Provide selection and investigation of status display for individual PS modules.

Chemical / Metrological Control Systems

In the second part of the present system, as described below, a chemical / metrological control system is provided. In the chemical analysis part of the system, three basic functions are performed, in particular sampling, analysis and cleanup. These functions include diagnostics, self-calibration, and calculations.

sampling

Sampling recovers liquid from a tank, sample loop, or grab sample vessel and delivers it to an assay cell. For titration and / or analysis where the correct amount of sample is required, the sample syringe is circulated to a pump in the sample and purges any other liquid. Several cycles of the sample are delivered to a beaker to ensure a typical sample. During this phase both a timer and a sample arrival detector are used to confirm that the sample has reached the appropriate time frame for the analysis to proceed. The beaker is thoroughly cleaned before the final sample volume is dispensed. For assays where the sample is tested directly without dilution, the liquid is pushed into the assay beaker by the pressure in the sample loop or drawn by the eductor.

analysis

The analysis is performed after the sample is delivered to the cell. Titration analysis can be performed with any conditioning reagent delivered by gravity through the solenoid valve. The titrant is delivered by a syringe controlled by a stepper motor. The titrant is added continuously during analogue readings to determine the end point. Once the end point is known, the beaker is cleaned and the test is repeated until the results are within user-defined error. A minimum of 3 repetitions are required and a maximum of 9 repetitions are allowed. As soon as the results are satisfactory with the discontinuous analysis, the analyst performs a thorough cleanup to avoid cross contamination.

Cleanup

The cleanup procedure cleans all analyzer components that come into contact with the sample solution. This begins with purging the air through the rotary valve (s) and the filter. If the sample fails to clear through the line, an error condition is generated in subsequent analysis that warns of low air pressure. Once cleaned by air, bursting wash water is activated to maximize the cleaning effect, and sample syringes, if used, are circulated until they are cleaned (depending on the process in which the analyzer is used, there may be no flushing of the sampling line). have). After this, the direct filling line into the beaker is washed.

Grab samples

A bottling sample at the grab sample seafer port may be provided to the analyzer for analysis. For optimal results the sample concentration should be within the specified range (warning limit) of the parameter being tested. Various methods can be used to analyze grab samples.

pH electrode calibration

pH calibration is performed prior to analysis using the pH electrode after a user-specified time after the final pH calibration. Calibration uses two pH buffers to determine the slope and offset of the pH electrode. Stable reads are obtained with one buffer and then the beaker is washed and the rest are read. The slope value is sent to the system manager to let the operator know the state of the electrode. The slope and the offset value are taken by the analyst and the voltage reading is converted to a pH value. The number of calibrations is set via the analysis structure table register specified in this aspect as "Hours Calibration Valid".

ORP electrode calibration

Since ORP electrodes are used for differential titration rather than absolute titration, no calibration is necessary. However, measurement of electrode sensitivity is desired because it may vary depending on the application. The electrode sensitivity, corrected for the ratio of the actual response to the ideal response, is recorded after each analysis and can be viewed in the system manager along with other analyzer parameters.

Chemical supplement

The replenisher can execute instructions entered into the system manager. The replenisher simultaneously controls the delivery of multiple feedstocks to multiple processes. When the flow rate is monitored and chemical delivery reaches the required amount, the feed is automatically shut off. The total chemical delivered is recorded by the replenisher for each feedstock. These values are used for low level alarm operation. Full and other information is available to the operator and remote computer.

Chemical Blends and Distribution Systems

In an embodiment of the invention, the chemical blend and distribution system comprises an HCl chemical feedstock cabinet designed to hold two 10 L containers of HCl. The system delivers the mountain to two locations, alerts the operator when the acid level is low, and warns the operator when it is empty. Some hardware and accessories used with this system

ㆍ shelf for pump cart and container

Air valve (× 2), pump (× 2) and filter (× 2)

ㆍ 2nd storage, leak detection and interlock

ㆍ Fittings for installations and joints, including Fe feedstock storage containers, which are automatically filled to user-defined levels and designed to be dispensed as needed in chemical mix support tanks

ㆍ Storage Container

Filling pumps, valves and filters

ㆍ Delivery Pump and Valve

ㆍ Level control-high level of fault, full, filling, empty

ㆍ 2nd storage, leak detection and interlock

ㆍ Fittings for facilities and joints

ㆍ Water Inlet Valve End Clean Up Spray Gun

• An electrical package containing embedded controller and I / O.

Chemical metrology control system

The system designs samples, analyzes solutions from both mixing tanks, and adjusts chemical supplements based on the results of the analysis. The metrological system is programmed to perform the following tasks based on a user-defined schedule.

ㆍ weight monitoring and adjustment

Nickel analysis and regulation-measurement up to ± 1.0% of range

ㆍ Iron analysis and regulation-measurement up to ± 0.5% of range

ㆍ pH monitoring and regulation- measurement up to ± 0.01 pH unit

ㆍ Amp min supplement option of HCl, Fe and water

System Manager-Operator Interface

In an implementation aspect of the present invention, the system manager is designed to run on an IBM compatible PC and provide the operator with control of all procedures and electro-mechanical and computerized components and subsystems. The system manager also provides the operator with a complete history, charts and graphs of alarms and warnings and all parameters monitored and / or controlled by the system. The parameter is

ㆍ feedstock level, inventory and usage history

ㆍ feedstock pump and valve control

ㆍ chemical, blend, mixing, electroplating and cleanup routines

• Includes an air control end motor.

Process control parameters

ㆍ feedstock filter pressure

ㆍ Recirculation Flow Rate

ㆍ Mix Tank Temperature

ㆍ mixed tank level

ㆍ density

Nickel

ㆍ Iron

• includes pH.

Summary of the invention

The prior and other objects are achieved by the present invention which provides a chemical control system for controlling the chemistry of a chemical solution having a predetermined chemical component in a plating system. According to the present invention, the control system uses a mixing container for containing the plating liquid and a holding container for containing the plating liquid transferred therefrom. The delivery of the exact predetermined amount of the predetermined component of the plating liquid is carried out by a precise delivery batch. The amount of the desired ingredient is delivered by precise delivery batch to the mixing and holding container. The plating liquid is transferred by a transfer pump between the mixing and holding container. In addition, the nitrogen gas source provides humidified nitrogen gas with a predetermined relative humidity depending on the temperature of the solution in each mixing or holding container to which they are delivered. This humidified nitrogen prevents the plating liquid from evaporating and also prevents the plating liquid from acquiring or releasing water.

Nitrogen gas is humidified by the same bubbling through a column of deionized water in thermal communication with a tank of chemical solution. The humidified nitrogen gas is then released to the tank where they form a layer on the plating liquid as described. The degree to which the nitrogen gas is humidified is a function of the column depth at which the nitrogen source gas is placed to release the nitrogen source gas to the deionized water. Each mixing and holding tank is provided with a connected column of deionized water to perform the relative humidity control of the nitrogen gas.

According to a further aspect of the invention there is provided a precise delivery arrangement for a chemical control system. An air pump having a pump inlet for receiving the delivered chemical and an outlet for discharging the pumped chemical is coupled with an orifice of a predetermined internal size. The orifice is then coupled with the flow meter to indicate the flow rate of the chemical through the orifice.

In one aspect, the air pump is a double displacement double diaphragm pump. In an embodiment, the air pump is structured to pump chemical at a chemical flow rate of approximately 50 ml per minute to approximately 2 liters per minute. Preferably, the chemical is allowed to flow at a rate of approximately 100 ml per minute to 1 liter per minute. Preferably, the air pump is considered to be about 2 to 10 times the chemical flow rate, preferably at least about 4 times the chemical flow rate. In addition, in one aspect, the orifice has an inner diameter of approximately 0.010 "to 0.090". In an embodiment of the invention, the inner diameter is approximately 0.030 "to 0.060".

Relationship to Other Applications

This application claims the benefit of US Provisional Application No. 60 / 083,811, filed May 1, 1998.

Technical Field

The present invention generally relates to chemical process control systems, more specifically to chemical analyzers that perform a number of basic functions, in particular sampling, analysis, mixing, replenishment, and cleanup, and additionally diagnostic, self-calibration, and calculation functions. It's about the system. The invention also relates to a system for humidifying nitrogen gas to a predetermined relative humidity level, and to calibration of an on-line pH sensor using an off-line pH sensor.

An understanding of the invention will be helpful by reading the following detailed description in conjunction with the accompanying drawings, in which

1 is a partial schematic diagram of an analyzer manager system for analyzing and controlling chemicals, in particular Ni (nickel), Fe (iron), and pH in a chemical processing system in certain illustrative embodiments of the present invention;

2 is a partial schematic diagram of a chemical replenisher system for supplying HCl and Fe feedstock and deionized water (DI) in this particular illustrative embodiment of the invention,

3-5 are top, end and front views, respectively, of a NiFe blend and distribution system made in accordance with the present invention;

6 is a schematic diagram of a system for controlling chemicals in a holding and mixing tank of a NiFe plating system,

FIG. 7 is a diagram of a graphical user interface (GUI) screen of the state conditions of the system as seen in a logic controller, and FIG.

8 is a diagram of a graphical user interface (GUI) of the analyzer conditions of the system as seen in a logic controller.

1 is a partial schematic diagram of an analyzer manager system for analyzing and controlling chemicals in a chemical processing system. As shown, analyzer 100 analyzes nickel (Ni), iron (Fe) and pH components and chemical baths (not shown in this figure) that are plating solutions in this embodiment of the invention. All control software incorporated into the analyzer 100 is recorded with a flowchart language tool designed with Opto 22. The use of such software significantly reduces startup, maintenance and upgrades, and modification costs. This flowchart language symbol allows the entire program to be visualized, operated, monitored and changed in a flowchart form. In diagnostic mode, flowchart symbols lighten as they are activated and this operation can be stopped, single-stage or signaled. Key Flowchart Language symbols are linked to a wide array of digital and analog I / O hardware that is readily available and integrated with software to provide a complete package.

FIG. 2 is a partial schematic diagram of a chemical replenisher system replenishing HCl and Fe feedstocks in this particular illustrative embodiment of the present invention. The replenisher also supplies deionized water. The refiller 200 is shown as a constant storage of feedstock and deionized water to be dispensed. Deionized water is maintained in zone 201 of refiller 200. HCl is stored in zone 202 and Fe is contained in zone 203. The material stored in this replenisher is provided to the holding and mixing tank and will be described below in FIG. 3. In this particular illustrative aspect of the invention, the refiller 200 is provided with a local water gun 205 which provides a deionized water source for cleaning and emergency cleaning of the components.

3-5 are top, end and front views of the NiFe blend and distribution system 300, respectively. The distribution system 300 is shown to have a mixing tank 302, a holding tank 303, a heater / cooler 304, a zone 305 for the pump, a filter and a valve and also a second receiving zone 307. The mixing tank 302 is provided with a mixer 310 that starts along the face 302 of the mixing tank near the top and extends to the center of the tank and functions to form a swirl pattern (not shown) at the bottom. Therefore, the vortex pattern sweeps all areas of the tank. The mixer is located off-center at an angle to maximize shear and mixing effects.

In this aspect of the invention, the mixing tank 302 and the holding tank 303 are lined with Teflon ^R material (not explicitly specified). It is desirable to remove most tank seams (not shown) while maintaining the Teflon ^R material in contact with the solution (not shown in this figure). In an alternative embodiment (not shown), a seamless tank formed of high purity PVDF is provided.

Also in the present invention, the second receiving zone 307 is arranged to be about ½ of the height of the mixing tank 302 and the holding tank 303. In this aspect, the second containment zone 307 has a capacity of approximately 1500 gal, corresponding to approximately 110% of the total volume of the holding and mixing tank. The receiving area also has a sufficient volume to accommodate all pumps and piping.

6 is a schematic diagram of a chemical process system 400 for controlling chemicals in each of the holding tanks and mixing tanks 302 and 303 of a NiFe plating system. It is displayed similarly to the elements of the structure already described. The mixing tank 302 is shown to contain a plating liquid 402 at a level lower than the high warning level 403. In this particular illustrative embodiment of the present invention, the mixing tank 302 has a 200 gallon capacity and operates at 106 gallons (400 liters) and the holding tank 303 has a capacity of 250 gallons and operates at 220 gallons (1000 liters).

All liquids delivered to the mixing tank are monitored with the use of flow sensors to achieve a regeneration of ± 2% in this embodiment. The accuracy level can be made to reach the level of regeneration with proper calibration. The flow of all liquid into the mixing tank 302 is identified with an in-tank level sensor 405 which provides a means of cross-checking between the flow sensor and the liquid level sensor. Preferably, the level sensor 405 is arranged to operate in its most straight and repeating region. This allows the fluid to be delivered in a stable manner over a long time without the need for recalibration after a short time.

In a preferred embodiment of the present invention, the level sensor 405 is a pneumatic device that facilitates continuous sensing of levels. This type of sensor is accurate, trouble free and unlike external proximity sensors, will not malfunction due to light crystalline tank wall build up or other changes in environmental conditions such as humidity. The air pressure sensor is not affected by tank wall build up, foaming, agitation, temperature, humidity, RF interference or electrical noise. The air pressure sensor will typically not require adjustment after installation. In addition, as can be seen from FIG. 6, the level sensor 405 provides a continuous measurement along the total depth of the mixing tank 302. This meaningful feature allows for immediate inventory of the tank contents used by the continuous monitoring of pump performance and control software (not shown) for verification of flow sensor accuracy. It should be understood that the gas flow rate in the level sensor is very slow at 10 cc / min to minimize dehydration of the plating solution. The inventors have tested here to find that low flow gas level sensors have essentially no detrimental effects on processes resulting from dehydration.

Nitrogen 407 is delivered to the mixing tank 302 in a particularly advantageous manner. The tank nitrogen vent gas is humidified to prevent dehydration / concentration of the solution. As shown, a vertical column 408 of deionized water is provided in communication with the mixing tank 302 and the nitrogen gas is humidified by receiving the vented nitrogen in the form of fine bubbles. Deionized water is slowly supplied to the column 408 through the needle valve 409 and flooded through an inverted U-shaped tube 410 to maintain a predetermined level and prevent nitrogen gas emissions. When nitrogen gas reaches the surface of deionized water and is released, it reaches approximately 95% to 99% relative humidity. Relative humidity can be controlled by the degree of immersion of the nitrogen gas outlet in column 408. This is sufficient to prevent almost all plating liquid moisture evaporation. In addition, the liquid column 408 is attached and insulated on the side of the mixing tank so that the temperature of the water column is the same as that of the plating liquid, ensuring accurate humidity compared to the solution tank in air space conditions. The humidified nitrogen gas is then delivered to the mixing tank 302 to form a gas blanket over the plating liquid 402. This method prevents over-humidification of the nitrogen gas that will cause solution growth, as can occur with conventional fog humidifiers when they are unbalanced.

The holding tank 303 is supplied with a level monitor device 415 similar to that described above with respect to the mixing tank 302. Nitrogen gas 417 is also delivered to column 418 to form bubbles of nitrogen gas therein. Deionized water is led to the column through needle valve 419 and excess deionized water is drained to U-shaped outlet 420. In this particular illustrative embodiment of the invention, the nitrogen gas is humidified in a similar manner as described above for the liquid column 408.

Deionized water is provided to the mixing and holding tanks. As shown, deionized water source 430 is led to mixing and holding tanks through pressure regulators 431 and 432 and air valves 435 and 436, respectively. In both cases, deionized water enters the tanks as sprays to clean or fill each tank and reach all areas. The pressure regulator ensures that a complete cone of flow and constant velocity are achieved from each spray head. In an implementation aspect of the present invention, it is important to maintain a moderate constant pressure since the non-uniform pressure will cancel the cleaning effect and cause unnecessary control system flow rate warnings.

In one aspect of the invention, the solution delivered from the mixing tank 302 to the holding tank 303 reacts with the air supplied from the regulated and filtered air supply 451 and the electric valve 452 to provide a pneumatically actuated bellows pump. Promoted by 450. It is therefore desirable that the delivered solution is at a controlled temperature before entering the holding tank 302. Otherwise, it will be difficult to maintain the temperature of the holding tank at the specified ± 0.1 ° C during delivery.

Fluid from the holding tank 303 acts on the plating process 460 (not shown) by the operation of the bellows pump 465. The pump operates in response to air supplied from source 451 and is controlled via electric valve 467.

In a specific description aspect of the invention, there is provided a backup recycle pump 469 that serves to minimize system downtime when pump maintenance is required. In this aspect, the pump switch-over is performed automatically at the operator's request, controlling the air valve 470.

Bellows pumps (465,469) are ultrapure Teflon ^R bellows manufactured by White Knight. The model AT300 bellows pump carries 10-20 gpm depending on the pressure head. These pumps are suitable for holding / dispensing tank recirculation loops. The model AT100 bellows pump carries 5-8 gpm and is suitable for mixing tank recirculation, filtration, and delivery to a holding tank (bellows pump 450). Because these pumps are characterized by low pulsation, pulse dampers are not commonly used.

In bellows pumps 465 and 469, these pumps are associated with air valve 470 and filter 477, respectively. Control on valve 470 allows automatic switching of bellows pumps and filters, facilitating pump maintenance, and filter replacement. In a detailed description aspect of the invention, the automatic switch is deployed across the filter and responds to a differential pressure monitored by differential pressure sensor 478.

In an embodiment of the invention, three successive levels of filtration are provided. Each level is sequentially finer in size to prevent initial loading of the filter and to provide the finer filtration needed most. The first stage of filtration is in the form of a strainer 473 having a size of 10 microns located at the feedstock outlet. The second level of filtration corresponds to the filter 475 at the outlet of the mixing tank 302. Filter 475 is a 1 micron filter. The third level of filtration corresponds to a 0.2 micron filter 477 at the outlet of the holding tank 303. The ball valve 480 can be operated manually and allows the equipment to be disconnected for shutdown and maintenance.

In this aspect of the invention, the respective pumps 510, 511 shown in FIG. 6 are used so that the delivery of the correct amount of chemical components to the mixing container, the holding container, or the plurality of mixing and holding containers is coupled to the trainer 473. Is achieved. In this specific embodiment of the present invention, the pumps 510, 511 are pneumatic, positive displacement double diaphragm pumps that achieve a limited maximum closed induction pressure by air operation, but nevertheless achieve a reasonably high dynamic range. Commercial pumps suitable for the practice of this aspect of the invention are available from ARO. In this specific embodiment, a WILDEN Model P.025 pump is used. As described herein, these pumps are relatively inexpensive and require minimal maintenance, which achieves high accuracy and accurate delivery of chemicals.

As shown, pump 510 is arranged to pump HCl from an HCl source in region 202 and pump 511 is also arranged to pump Fe from Fe source in region 202. In this specific embodiment of the invention, the HCl source is a 10 liter bottle and the Fe source is a 40 liter tank.

Each pump 510, 511 is coupled to a respective orifice 513, 514 associated at its outlet. In this embodiment, the orifice has an inner diameter of approximately 0.010 ″ to 0.090 ″. Preferably, the orifice has a diameter of approximately 0.030 ″ to 0.060 ″. In a typical embodiment, the inner diameter is 0.040 "to 0.050". The orifice is coupled to each of flow meters 516 and 517 which are conventional paddle wheel style flow meters in an aspect of the present invention. Although these inexpensive flowmeters have non-linear characteristics, the combination of pump and orifice is within a narrow range, preferably within the linear region of the characteristic response curve of the flowmeter, but in no case non-linearity is affected. This is achieved because it maintains a flow rate that is narrow enough to be ignored. Thus, with relatively inexpensive components, surprisingly high accuracy is achieved for the delivery of chemicals. The precision delivery batch of the present invention may supply supplemental chemicals to one or more mixing or holding tanks, for example eight such tanks.

In order to provide continuous and accurate pH readings, two pH sensors are used. One pH sensor (not shown) is located in the analyzer 100 that is automatically calibrated daily or at certain other defined intervals. As a result of these precise calibrations, these off-line pH sensors provide accuracy above ± 0.02 pH and repeatability above ± 0.01 pH. In this operation, the off-line pH sensor is off-line (ie, not continuously exposed to a sample of the chemical solution used in the plating system) and exposed to a calibration liquid with a known pH value and a reading is made. Immediately thereafter, the off-line pH sensor is placed in the same batch of samples into which the on-line pH sensor is fed (ie on-line sample) and a second reading is performed. This second reading is compared to the reading of the on-line pH sensor, which is a pH sensor 485 located in the holding tank 303. The difference between on-line and off-line pH sensors for the sample solution constitutes the corrections made to achieve the correct value of the sample solution pH. The on-line sensor is immersed to provide continuous process readings. The sensor is calibrated to read the same as the calibrated (off-line) sensor whenever the pH reading is read in the calibration system. Deviations exceeding the user-defined amount are reported as a warning. The high quality research pH sensor drifts to around 0.002 pH per day, with the usual offset value used to provide this calibration is less than 0.01 pH.

Specific gravity is monitored by specific gravity unit 487. This specific gravity monitor is an Anton Paar Model DPR407NYB transducer placed in the recycle loop. These commercial specific gravity sensors have a published repeatability of ± 0.00001 g / ml. In some aspects, specific gravity sensor 487 is provided with an associated partial bypass valve (not shown) to avoid causing too much flow restriction.

In some aspects of the invention, the mixing time is minimized in the mixing tank 302 by a liquid ejector (not shown) from the injection line to the tank. These ejectors use pumps only to increase the volumetric flow in a tank several times. Liquid ejectors, in contrast to mixers, are passive devices that do not require any power, special maintenance, or high speed pumps.

6 also shows an anode 490 electrically connected to a rectifier 491 to achieve dummy plating. In some aspects of the invention, a small plating cell (not shown) located above the mixing tank 302 is provided such that dummy plating occurs in more separated accessible areas. This will allow the anode and cathode to separate from the mixed solution and to be cleaned at any time independent of the mixing tank activity. In this arrangement, the recycle NiFe solution can be routed through the plating cell to flood or bypass the mixing tank 302 and route directly to the mixing tank. Certain material that falls off the anode or cathode collects at the bottom of the cell which is routed to be discharged rather than passed to the subsequent tank.

The figure shows a heat exchanger 495 at the outlet of the holding tank 303. This makes it possible to feed the solution into the recycle loop at the most consistent and stable temperature. Heat exchanger 495 is a water-jacket device located just in front of the recycle loop. Thus, accuracy is maintained and offsets resulting from changes in required speed or flow rate are prevented. The temperature of the heated water is adjusted according to the desired NiFe solution discharge temperature, not the internal water temperature. Other heater types can be used in the practice of the present invention.

7 is an illustration of a graphical user interface (GUI) screen of the state conditions of the system as represented by a logic controller (not shown). As shown in this figure, screen 500, which may be in the form of a conventional cathode ray tube, describes various state conditions for system 400. Screen 500 is just one of a number of arrangements that may be provided to describe the condition conditions of the system. In addition, the selection of the appropriate button yields another screen that provides information related to the system history, an indication of whether a particular tank is on-line, replenishment status, error status, and the like.

8 illustrates a graphical user interface (GUI) screen 501 of analyzer conditions of the system, as represented by a logic controller (not shown). As shown, this screen depicts a schematic sample process and provides an indication of parameters in the ongoing analysis. In addition, it is only one of several display formats that may be used in the practice of the present invention.

Although the present invention has been described in particular aspects and applications, those skilled in the art, in light of these teachings, create additional aspects without exceeding or departing from the scope of the claimed invention. Accordingly, the drawings and detailed description herein are provided to assist in understanding the present invention and are not intended to limit the scope thereof.

Claims (35)

A mixing container for containing a plating liquid; A holding container for containing a plating liquid delivered from the mixing container; A precision-delivery arrangement for delivering an accurate predetermined amount of the desired component of the plating liquid in a selectable combination of mixing container and holding container; A delivery pump for forcing a plating liquid to be transferred from the mixing container to the holding container; And A nitrogen gas source (the humidified nitrogen gas is humidified to a predetermined relative humidity relative to the temperature of the plating liquid in the mixing container) to provide the mixing container with a flow of nitrogen source gas to which deionized water is added to form humidified nitrogen gas. A chemical control system for controlling the chemistry of the chemical solution having a predetermined chemical component in the plating system. The chemical control system of claim 1, wherein the plating solution is used in a NiFe plating system. The chemical control system of claim 1, wherein the nitrogen gas source contains deionized water and comprises a column for releasing humidified nitrogen gas, the column being in thermal communication with the mixing tank. 4. The chemical control system of claim 3, further provided with a nitrogen source gas outlet arranged to discharge the nitrogen source gas into deionized water in the column. 5. A column according to claim 4, wherein the nitrogen source gas outlet is arranged to discharge the nitrogen source gas at a variable selectable position along the column and the nitrogen source gas outlet is arranged such that the relative humidity of the humidified nitrogen gas releases the nitrogen source gas into the deionized water. Chemical control system that reacts to the position along. The chemical control system of claim 1, further provided with an additional nitrogen gas source for providing the holding container with a flow of additional nitrogen source gas that is humidified with a predetermined relative humidity relative to the plating liquid temperature in the holding container. 7. The chemical control system of claim 6, wherein the additional nitrogen gas source contains deionized water and comprises an additional column for releasing humidified additional nitrogen gas, the column being in thermal communication with the holding tank. 8. The chemical control system of claim 7, further provided with an additional nitrogen source gas outlet arranged to release additional nitrogen source gas to deionized water in the additional column. 9. The additional nitrogen source of claim 8, wherein the additional nitrogen source gas outlet is arranged to discharge the additional nitrogen source gas at a variable selectable position along the additional column, such that the relative humidity of the humidified additional nitrogen gas releases the additional nitrogen source gas into the deionized water. Chemical control system that reacts to a location along an additional column in which gas outlets are disposed. The chemical control system of claim 1, wherein the precise delivery batch comprises a continuous batch of source pump and orifice. The chemical control system of claim 10, wherein the source pump is an air pump. 12. The chemical control system of claim 11, wherein an additional mixing container is provided, and the precise delivery batch is arranged to deliver to each mixing container and the additional mixing container an accurate predetermined amount of a predetermined component of the plating liquid. 12. The chemical control system of claim 11, wherein the source pump is a double displacement double diaphragm pump. 12. The chemical control system of claim 11, wherein the source pump is arranged to pump predetermined components of the plating liquid at a component flow rate of approximately 100 ml / min to 10 l / min. 15. The chemical control system of claim 14, wherein the source pump has a rated flow rate of approximately three to seven times the component flow rate. The chemical control system of claim 15, wherein the source pump has a rated flow rate of at least approximately four times the component flow rate. The chemical control system of claim 14, wherein the orifice has an inner diameter of approximately 0.010 ″ to 0.090 ″. 18. The chemical control system of claim 17, wherein the orifice has an internal diameter of approximately 0.040 "to 0.050". The method of claim 1, A mixed air level sensor for providing an indication of the plating liquid level in the mixing container, and A chemical control system further provided with a holding air level sensor for providing an indication of the plating liquid level in the holding container. 20. The chemical control system of claim 19, wherein a mixing and holding air level sensor is arranged to provide a measurement along a predetermined length of each associated mixing and holding container. 20. The chemical control system of claim 19, wherein each of the mixing and holding air level sensors is arranged to use a gas flow rate on the order of 10 cc / min. The chemical control system of claim 1, wherein the delivery pump is an air operated bellows pump. The chemical control system of claim 22, wherein the delivery pump is a Teflon ^R bellows. The chemical control system of claim 1, further comprising a dummy plating anode in the mixing container. The chemical control system of claim 1, further provided with a chemical analyzer system for analyzing the plating liquid in the mixing container. 27. The chemical control system of claim 25, wherein the chemical analyzer system analyzes the plating liquid in the holding container. An air pump having a pump inlet for receiving a chemical to be delivered and an outlet for discharging the chemical to be pumped; An orifice coupled to the outlet of the air pump; And A precision delivery arrangement for a chemical control system, comprising a flow meter coupled to the orifice to provide an indication of chemical flow rate through the orifice. 28. The precision delivery deployment of claim 27 wherein the air pump is a bi-displacement double diaphragm pump. 29. The precise delivery deployment of Claim 28 wherein the air pump is arranged to pump chemical at a chemical flow rate between approximately 50 ml / min and 2.0 l / min. 30. The precision delivery deployment of claim 29 wherein the air pump is arranged to pump chemical at a chemical flow rate of approximately 100 ml / min to 10 l / min. 30. The precise delivery arrangement of Claim 29 wherein the air pump has a rated flow rate of approximately 2 to 10 times the chemical flow rate. 32. The precise delivery arrangement of Claim 31 wherein the source pump has a rated flow rate of at least approximately four times the chemical flow rate. 30. The precise delivery arrangement of Claim 29 wherein the orifice has an inner diameter of approximately 0.010 " to 0.090 ". 34. The precise delivery arrangement of Claim 33, wherein the orifice has an inner diameter of approximately 0.030 "to 0.060". Primary immersion of the off-line pH sensor in the calibration sample; Take a calibration reading of the off-line pH sensor while performing the first immersion step; Secondary immersion of the off-line pH sensor in the sample chemical; Take a sample reading of the off-line pH sensor during the second immersion step; Comparing the off-line sample reading and the on-line sensor sample reading; Calibrating the on-line sensor sample reading according to the comparing step, measuring the sample chemical in the chemical control system, and calibrating the pH measurement batch, the system is a type in which the on-line pH sensor is immersed in the sample chemical. Way.