EP1932953B1 - Galvanic process with analysis of the electrolytic bath through solid phase extraction - Google Patents

Description

Field of the invention

The present invention relates to a method for the electrodeposition of a metal layer from an electrolyte bath, wherein the concentration of at least two components of the electrolyte bath is monitored by means of a column for solid-phase extraction.

Background of the invention

The galvanic deposition of metal layers from electrolyte baths is widely used industrially. In this case, in addition to a compound of the metal to be deposited or of the metals to be deposited, the electrolyte bath generally contains further components which are necessary for carrying out the deposition process and for improving the quality of the deposited metal layer. These substances are organic compounds. Examples of such components are grain refiners, wetting agents, brighteners, complexing agents, inhibitors. These components are generally more or less rapidly consumed, destroyed or removed from the bath by carry-out when performing the deposition process. The concentration of components therefore decreases more or less rapidly over time. Therefore, in order to permit optimum performance of the deposition process over an extended period of time, it is necessary to monitor the concentration of one or more components of the electrolyte bath and replace the consumed or destroyed amount of the component as needed by adding fresh component to the electrolyte bath.

The monitoring of the concentration of the component (s) of an electrolyte bath requires the determination of the concentration of the component (s) in the electrolyte bath at regular time intervals. So far, this is often done in such a way that the electrolyte bath individual samples are removed manually and these are optionally subjected to a sample enrichment and purification of a chemical and / or physical analysis. Here, the individual analysis steps of the separation of the additives, purification and concentration determination are carried out separately. In addition to the increased expenditure of time and the resulting additional costs, the result is available only considerably delayed for a valuation. The goal of ensuring increased process safety and enabling rapid intervention if concentrations or concentration ratios change or degradation products of the additives accumulate in the electrolyte is very limited, if any, achievable. Often it is not possible at the place of manufacture and thus the place of sampling to carry out a corresponding bath analysis in a timely manner. As a rule, the operator of the production facility therefore relies on the help and the timetable of third parties in order to carry out the analysis, which is of immense importance for the process control and the quality of his products, unless he wishes to invest in the appropriate analysis facilities and qualified personnel.

State of the art

Solid Phase Extraction (SPE) is the most widely used method for sample enrichment and purification, ie, sample preparation method, for modern liquid chromatography. It is used in particular for the analysis of active pharmaceutical ingredients and in environmental technology Enrichment of the substances to be determined used in the water analysis.

For this purpose, the components to be extracted are enriched on special adsorbents and then eluted with a solvent. Optionally, a vacuum can be applied to the cartridges used.

Solid phase extraction has the great advantage over liquid-liquid extraction (LLE) of being able to handle much lower volumes of solvent, resulting in higher analyte concentration in less time. In addition, the separation is more complete compared to the LLE because the choice of adsorbent and eluent allows for a wide range of polarity and optimal extraction of the desired components of the solution.

According to the prior art, the above-mentioned sample enrichment and purification is carried out as a separate step before the actual separation and determination of the substances of interest. This separation and determination is often performed by subsequent liquid chromatography (e.g., HPLC, UPLC), i. The sample preparation and the actual determination are carried out in several consecutive steps.

1. (a) Entnahme einer Probe des Bads zur Abscheidung von Kupferschichten
2. (b) Festphasenextraktion der beiden zu bestimmenden Additive in einem Schritt mit einem Styrol- / Divinylbenzol-Säulenmaterial
3. (c) Trennung der Additive mittels HPLC
4. (d) quantitative Bestimmung der Additive mittels UV-Spektrometrie

D'Urzo et al. (Journal of the Electrochemical Society, 152, 2005, p. C243 and p. C697 ) describe the monitoring of two classes of organic additives in acidic copper baths by solid phase extraction and HPLC analysis, comprising the following steps:

1. (a) Taking a sample of the bath to deposit copper layers
2. (b) solid phase extraction of the two additives to be determined in one step with a styrene / divinylbenzene column material
3. (c) Separation of the additives by HPLC
4. (d) quantitative determination of the additives by means of UV spectrometry

1. (a) Probenahme
2. (b) Festphasenextraktion
3. (c) HPLC-Trennung
4. (d) UV-Detektion

Johnson et al. (Metal Finishing, October 1985, p. 49 ) describe the determination of three organic components used as additives in acidic tin baths

1. (a) Sampling
2. (b) solid phase extraction
3. (c) HPLC separation
4. (d) UV detection

A disadvantage of these methods is the use of a complex HPLC step for the separation of the organic compounds before their quantitative determination.

The quasi-continuous monitoring of a plating process becomes viable when the process and / or bath conditions change faster than can be measured using traditional manual analysis and automation techniques. This is especially true for processes with a narrow concentration range, small bath volumes and high throughputs (high deposition rate, introduction and removal).

Description of the invention

The invention has for its object to provide a method for the electrodeposition of a metal layer of an electrolyte bath, wherein the concentration of at least two Components of the electrolyte bath can be monitored in a simple manner. In particular, it should be possible to determine the concentration of the at least two components in a short time and using small volumes of solvent. As a result, the quasi-continuous monitoring of the concentration of at least two components should be possible. In addition, it should be possible to monitor the concentration of several components virtually simultaneously.

These objects are achieved by a method of electrodepositing a metal layer from an electrolyte bath, wherein the concentrations of at least two components of the electrolyte bath are monitored by performing the following steps: (a) a sample is taken from the electrolyte bath; (b) the sample is fed to a solid phase extraction column containing a solid sorbent; (C) the column is subjected to a washing process with a first eluent, wherein the at least two components remain on the column and unwanted components are eluted from the column; (d) the at least two components are eluted from the column by means of a second eluent; (e) the concentrations of the at least two components in the eluate obtained in step (d) are determined without separating the components.

The present invention provides for the first time a method for the automatic, quasi-continuous solid-phase extraction of the components to be determined (in particular organic additives) with subsequent direct concentration determination without the requirement of prior separation of the components.

The direct determination of the concentration of the components can be carried out by means of photometry, in particular UV detection, or by means of electrochemical detection methods, in particular polarography, or else by refractometry.

The present invention enables the analysis of the additives in particular of tin, tin / lead, zinc, copper, nickel electrolytes and of noble metal electrolytes, in particular palladium and gold electrolytes.

Brief description of the drawings

FIG. 1 shows a schematic representation of the stages of the sample application, the washing and the elution of the column for solid phase extraction according to an embodiment of the inventive method.

FIG. 2 shows a schematic representation of the stages of sample application, washing and elution of the column for solid phase extraction according to another embodiment of the method according to the invention.

FIG. 3 shows a schematic representation of the stages of sample application, washing and elution of the column for solid phase extraction according to another embodiment of the method according to the invention.

FIG. 4 shows a schematic representation of an analysis system for the method according to the invention with switching valves, wherein the sample or a washing solution in the forward direction are passed over the column for solid phase extraction and an optional collecting and mixing container is provided.

FIG. 5 shows a schematic representation of an analysis system for the method according to the invention with switching valves, wherein the eluent is passed in the reverse direction over the column for solid phase extraction and an optional collecting and mixing container is provided.

Description of the Preferred Embodiments

The invention provides a method of electrodepositing a metal layer from an electrolyte bath. The metal to be deposited is not particularly limited. In particular, the metal may be tin, tin / lead, zinc, copper, nickel, a noble metal such as palladium or gold, or a combination of these or other metals.

The method according to the invention makes it possible to monitor the concentrations of at least two components of the electrolyte bath. The components are preferably organic components of the electrolyte bath. The components whose concentration can be monitored include, in particular, flavones, chalcones, maltols, naphthols and UV-active ionic and nonionic surfactants. A component whose concentration is monitored may also be a grain refiner. The grain refiner may in particular be morin, e.g. used in electrolyte baths for the deposition of tin layers. The component may further be a conventional additive used in electrolyte baths for deposition of tin layers.

In the method according to the invention, the concentration of at least two components of the electrolyte bath can be monitored. The stages of sampling, the solid phase extraction, the washing process and the elution for the component to be monitored are preferably carried out simultaneously or in parallel. The determination of the concentration of the components takes place without the components being separated from one another. However, the determination of the concentration of the individual components is not necessarily simultaneous, but usually one after the other. However, the determination of the concentration of the individual components can preferably take place in one measuring cycle.

In the case of determination of the components in successive analysis steps, different sample volumes can be used for each component to be monitored, depending on the concentration of the particular component and the sensitivity of the determination method used.

In particular, the method according to the invention makes it possible to monitor components which differ greatly from one another with regard to their concentration in the electrolyte bath and / or their absorption coefficient ε and which can therefore not be determined simultaneously using conventional methods.

In the method according to the invention, a sample is first taken from the electrolyte bath. This can be done in particular by sucking in a small partial volume of the electrolyte bath via a pump.

The sample is then fed to a solid phase extraction column containing a solid sorbent. The sorbent is selected according to the solution character, polarity, hydrophilicity and lipophilicity of the substances to be separated. The macromolecular backbone of the sorbent is preferably a copolymer of divinylbenzene and N-vinylpyrrolidone or a crosslinked polystyrene (formed by copolymerization of styrene with divinylbenzene). The sorbent can also consist of silica (silica gel).

Surprisingly, in particular for the copolymer of divinylbenzene and N-vinylpyrrolidone (ie poly (divinylbenzene-co-N-vinylpyrrolidone)), a very good separation effect of the components to be determined from the aqueous matrix of the electrolyte bath has been demonstrated. In addition, it is characterized in particular by both a hydrophilic and a lipophilic retention characteristic. This allows the use of aqueous, polar and nonpolar solvents for the extraction of analytes and thus covers a particularly wide range of applications.

, die spezifische Oberfläche beträgt bevorzugt etwa 831 m²/g, das Porenvolumen beträgt bevorzugt etwa 1.4 cm³/g, der durchschnittliche Partikeldurchmesser beträgt bevorzugt etwa 31.4 µm und der Anteil an Feinstoffen (< 10 µm) liegt bevorzugt bei etwa 0.1%. Poly(divenylbenzol-co-N-vinylpyrrolidone) mit diesen Eigenschaften sind kommerziell verfügbar (z.B. von Waters Corporation).The average pore diameter of the poly (divinylbenzene-co-N-vinylpyrrolidone) used, for example, as a sorbent is preferably about 82

, the specific surface is preferably about 831 m ² / g, the pore volume is preferably about 1.4 cm ³ / g, the average particle diameter is preferably about 31.4 microns and the proportion of fines (<10 microns) is preferably about 0.1%. Poly (divinylbenzene-co-N-vinylpyrrolidones) having these properties are commercially available (eg from Waters Corporation).

So far, poly (divinylbenzene-co-N-vinylpyrrolidone) found no use in electroplating.

As further column materials, those based on silica are also suitable, in particular RP18 (lipophilic character). RP18 means "reversed phase" with 18 C atoms in the side chain. This term is used for a particular stationary phase of liquid chromatography. In the RP phases, the polarity ratios are reversed compared to the normal phases. Nonpolar side chains are attached to a silica backbone or to a polymer. In general, silica-based column materials having 8 to 18 carbon atoms can be used.

Near the column inlet opening, the solid phase extraction leads to an accumulation of the components to be monitored.

The column is then subjected to a wash with a first eluent, leaving the at least two components to be monitored on the column and eluting undesired components from the column. The first eluents which may be used are in particular: water, dilute acid, methanesulfonic acid, acetates, carbonates, bases, or mixtures thereof, a mixture of alcohol and sulfuric acid or a mixture of alcohol and water. The eluents are, depending on the solution character, the polarity, hydrophilicity and lipophilicity of the substances to be separated.

The washing process also serves to wash out or filter out impurities and larger particles that can not pass through the column with the aqueous matrix. Otherwise, such particles would enter the measuring chamber in the subsequent elution step and adversely affect the measurement there.

The at least two components to be monitored are then eluted from the column by means of a second eluent. In particular, the following may be used as the second eluent: water, methanol, a mixture of water and methanol, alkanes, methyl chloride, alcohols, dimethyl sulfoxide, acetonitrile or mixtures thereof. The eluents are selected according to the solution character, the polarity, the hydrophilicity and lipophilicity of the substances to be separated.

The first eluent and the second eluent may be supplied to the column in the same direction as the sample of the electrolyte bath first supplied (see FIG. 1 ). This direction is referred to here as "forward".

Alternatively, the first eluent and / or second eluent may be fed to the column in the opposite direction (see Figures 2 and 3 ). This direction is referred to here as "backwards".

The reversal of the Elutionsrichtung can be realized in a simple manner by means of switching valves, as shown in the FIGS. 4 and 5 is shown. The valve setting allows adjustment of the flow direction. This process variant is preferred. In particular, a collecting and mixing container be provided to dilute the eluate before measuring if its concentration is too high.

By reversing the direction of elution, the extended column passage is avoided in the case of maintaining the flow direction during the elution. The exit path of the components to be monitored or of the undesired components is thereby shortened and the analysis time is considerably reduced. In addition, the reproducibility of the values is significantly improved.

Finally, the concentrations of the at least two components to be monitored are determined in the eluate obtained by elution with the second eluent. From the concentration in the eluate, the concentration of the component in the electrolytic bath can be calculated (based on the volume of the eluate and the volume of the initially charged sample).

The concentration can be determined photometrically. In this case, the eluate obtained by the elution with the second eluent is supplied to a measuring cell, where UV light is preferably radiated in perpendicular to the direction of flow from an external source and detected in a photometer and recorded by means of a computer program. The at least two components do not have to be separated for this purpose. Rather, it is possible to determine the concentrations of different components separately by using light of different wavelengths without separation of the components. The determination of the concentrations of the individual components can be carried out in succession. The determination of the concentrations of the individual components can also be carried out in different devices and using different sample volumes. A separation of the at least two components to be monitored from each other before the concentration determination, as carried out in known methods, preferably by means of chromatographic methods is, is in the inventive method, however, not required.

Rather, in the method according to the invention, a physical measuring method is selected in which the physical parameters of the at least two components are different so that a determination can be made without separation of the components.

• Photometrie, wobei sich die beiden Komponenten in ihren Extinktionskoeffizienten ε unterscheiden,
• Polarographie, wobei sich die beiden Komponenten in ihrem Halbstufenpotential unterscheiden, das eine charakteristische Größe für die Art des Depolarisators (Analyten) im gewählten Leitelektrolyt darstellt,
• Refraktometrie, wobei sich die beiden Komponenten in ihrem Brechungsindex η unterscheiden.

Suitable physical measuring methods include in particular:

• Photometry, where the two components differ in their extinction coefficients ε,
• Polarography, where the two components differ in their half-wave potential, which represents a characteristic variable for the type of depolarizer (analyte) in the selected guide electrolyte,
• Refractometry, wherein the two components differ in their refractive index η.

Other suitable measurement methods for concentration determination include electroanalytical methods such as coulometry and voltammetry. In addition, the mass spectrometry is suitable for determining the concentration.

In a preferred embodiment of the method according to the invention, the column is subjected to conditioning before the supply of the sample of the electrolyte bath. In particular, the following may be used as conditioning agents: methanol or an acidic solution. The use of acidic conditioning solutions is particularly advantageous in order to avoid the precipitation of poorly soluble substances and thus the clogging of the column. After conditioning or activation and prior to supplying the sample of the electrolyte bath, the column is equilibrated with water.

In the method according to the invention, the concentration of at least two components of an electrolyte bath can be monitored quasi-continuously. The term "quasi-continuous" means that the determination of the concentrations in a relatively short time interval is repeated regularly. The time interval can be, for example, 10 hours, 5 hours, 2 hours, 1 hour, 30 minutes, 10 minutes, or 1 minute. In the method according to the invention, the monitoring of the concentration of the at least two components of the electrolyte bath can advantageously be carried out automatically. The term "automatic" means that all steps of the procedure are performed without manual intervention.

In a preferred embodiment of the method according to the invention, the monitoring of the at least two components is combined with the control of a dosing system which supplies a fresh amount of the consumed or destroyed component to the electrolyte bath as needed to achieve a nearly constant concentration of the monitored components during operation of the deposition process. In the ideal case, a steady state is achieved in which all components that deplete are supplemented by a suitable dosing system and the components that accumulate are removed by appropriate regeneration measures.

The method according to the invention is easy to handle and offers a cost-effective alternative to manual sampling with subsequent sample enrichment and final concentration determination and to known methods with separation of the components to be monitored. By monitoring the economy of the invention, the quality and the Proof of quality and troubleshooting in current production are demonstrably improved.

For the first time, the present invention makes it possible to monitor at least two components of electrolytic baths in electroplating technology in a highly efficient, cost-effective, easy-to-handle and highly reproducible manner.

Examples

The invention will be explained in more detail below with reference to non-limiting examples.

1. 1. Kornverfeinerer (Morin)
2. 2. Additiv (Polymer, Tensid)

eines Elektrolytbads zu Abscheidung von Zinnschichten (StannoPure HSM^- der Atotech Deutschland GmbH) überwacht.It became the concentration of the components:

1. 1. grain refiner (Morin)
2. 2. Additive (polymer, surfactant)

of an electrolytic bath for deposition of tin layers (StannoPure HSM ^- Atotech Deutschland GmbH).

An Oasis HLB-Plus column (Waters Corporation, dimensions of the column: 4.6 × 21 mm, particle diameter 25 μm) was used for solid-phase extraction.

1. 1. Konditionierung der Säule mit 2,5 ml Methanol
2. 2. Equilibrierung mit 2,5 ml VE-Wasser (vollentsalztes Wasser) / 3,25 ml/l MSA (Methansulfonsäure, 70%)
3. 3. Probenaufgabe (Probenvolumen: 1,0 ml)
4. 4. Waschen mit 5 ml VE-Wasser / 3,25 ml/l MSA (70%)
5. 5. Eluieren mit 1,0 ml Methanol
6. 6. Photometrische Bestimmung bei 416 - 550 nm

To monitor the concentration of the grain refiner, the following steps were carried out:

1. 1. Conditioning the column with 2.5 ml of methanol
2. 2. Equilibrate with 2.5 ml DI water (deionized water) / 3.25 ml / l MSA (methanesulfonic acid, 70%)
3. 3. Sample application (sample volume: 1.0 ml)
4. 4. Wash with 5 ml DI water / 3.25 ml / l MSA (70%)
5. 5. Elute with 1.0 ml of methanol
6. 6. Photometric determination at 416-550 nm

• 1. Konditionieren der Säule mit 2,5 ml Methanol
• 2. Equilibrieren mit 2,5 ml VE-Wasser / 3,25 ml/l MSA (70%)
• 3. Probenaufgabe (Probenvolumen: 0,05 ml)
• 4. Waschen mit 5 ml VE-Wasser / 3,25 ml/l MSA (70%)
• 6. Eluieren mit 10 ml Methanol, 9 ml des Eluats verwerfen und 2 ml Methanol hinzugeben
• 8. Photometrische Bestimmung bei 226 nm

To monitor the concentration of the additive, the following steps were carried out:

• 1. Condition the column with 2.5 ml of methanol
• 2. Equilibrate with 2.5 ml DI water / 3.25 ml / l MSA (70%)
• 3. Sample application (sample volume: 0.05 ml)
• 4. Wash with 5 ml DI water / 3.25 ml / l MSA (70%)
• 6. Elute with 10 ml of methanol, discard 9 ml of the eluate and add 2 ml of methanol
• 8. Photometric determination at 226 nm

Claims (18)

1. Method for electrodepositing a metal layer from an electrolytic bath, wherein the concentrations of at least two components of the electrolytic bath are monitored, wherein the following steps are carried out:

   (a) a sample is taken from the electrolytic bath;

   (b) the sample is supplied to a column for solid phase extraction, which contains a solid sorbing agent;

   (c) the column is subjected to a washing procedure with a first eluent, wherein the at least two components remain on the column, and undesired components are eluted from the column;

   (d) the at least two components are eluted from the column by a second eluent; and

   (e) the concentrations of the at least two components in the eluate obtained in step (d) are determined without separating the components from each other.
2. Method according to Claim 1, wherein the metal is tin, zinc, copper, nickel or a noble metal.
3. Method according to Claim 2, wherein the noble metal is palladium or gold.
4. Method according to any one of the preceding claims, wherein the component to be monitored is a flavone, chalcone, maltol, naphtol or a UV-active non-ionic surfactant.
5. Method according to any one of the preceding claims, wherein the component to be monitored is a grain-refining agent or an additive.
6. Method according to Claim 5, wherein the grain-refining agent is morin.
7. Method according to any one of the preceding claims, wherein the sorbing agent is a copolymer of divinyl benzene and N-vinyl pyrrolidone.
8. Method according to any one of the preceding claims, wherein the first eluent is water, a diluted acid, a mixture of alcohol and sulfuric acid or a mixture of alcohol and water.
9. Method according to any one of the preceding claims, wherein the second eluent is water, methanol, a mixture of water and methanol or acetonitrile.
10. Method according to any one of the preceding claims, wherein the supply of the first eluent to the column in step (c) is carried out in the same direction as the supply of the sample in step (b).
11. Method according to any one of Claims 1 to 9, wherein the supply of the first eluent to the column in step (c) is carried out in opposite direction to the supply of the sample in step (b).
12. Method according to any one of the preceding claims, wherein the supply of the second eluent to the column in step (d) is carried out in the same direction as the supply of the sample in step (b).
13. Method according to any one of Claims 1 to 11, wherein the supply of the second eluent to the column in step (d) is carried out in opposite direction to the supply of the sample in step (b).
14. Method according to any one of the preceding claims, wherein the determination of the concentrations in step (e) is carried out by photometry, polarography, refractometry.
15. Method according to any one of the preceding claims, wherein the sequence of steps (a) to (e) is repeated at regular intervals of one minute to 10 hours.
16. Method according to any one of the preceding claims, wherein the monitoring of the concentration of the at least two components is carried out in combination with a dosing system, which, depending on the result of the determination of the concentrations, supplies the corresponding fresh amount of the component(s).
17. Method according to any one of the preceding claims, wherein a conditioning treatment of the column with methanol or an acid-containing solution and a subsequent equilibration of the column with water is carried out prior to step (b).
18. Use of poly(divinyl benzene-co-N-vinyl pyrrolidone) for the solid phase extraction of components of an electrolytic bath.

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