Analyze acid copper plating solution

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free pdf is currently available from academia.edu

A. You have not provided enough information. What acid? Copper plating or copper stripping. For control or for EPA?

For about $36 you can get a subscription to Metal Finishing which includes procedures for wet chemistry testing in its Guide Book. Also has lots of vendor information. It is one of the few good deals left. Hach and a few others make some drop test equipment and solutions. With the micro titrator, Hach's is very accurate. Drop testing is an approximation or an educated guess.

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Ed. note Nov. 6, 2017: The Metal Finishing Guidebook is now history, but you hopefully get a used copy or view it online.

"The Chemical Analysis of Electroplating Solutions"
by Terrance H Irvine

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A. If the acid is sulfuric acid or hydrochloric, titrate for the acid, 10 cc sample, dilute to 100 cc with water, Normal caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] to a methyl orange ⇦ this on eBay or Amazon [affil links] (yellow endpoint) or bromophenol blue ⇦ this on eBay or Amazon [affil links] (blue end).

1 ml N NaOH = 0.049 g H2SO4.
1 ml N NaOH = 0.0365 g HCl

Heavy metal content (if only Copper is present, Bingo)

10 ml sample, add 10 ml of 100 vol H2O2 and raise to the boil, heating until all oxygen is driven off, dilute to 200 ml, heat to 70 °C. Precipitate the iron using ammonia ⇦ this on eBay or Amazon [affil links] as in method 42, Then proceed as in method 43.

From Langford and Parker, Analysis of Electroplating and Related Solutions [on Amazon, ... on AbeBooks affil links].

Is this what you were looking for?

If so, I can get you the rest.

A. If you want to skip with the chemistry and just use a simple premixed test kit, contact Kocour Co. in Chicago Illinois.

regards,
Dave
SUNNYvale California

A. Phil, the concentration of "bluestone" or copper sulphate ⇦ this on eBay or Amazon [affil links] in your bath can be measured by using a Hydrometer to measure the Density. There are Tables available in most Electroplating Text books. Or you could measure the Density of the bath when it has just started to crystallize and settle on a Density slightly lower as your maximum limit. After dilution(cutting) the Density is taken and then you have a "range".

Good luck.

A. Further to Pat's suggestions, the SG tables are a combination of both the copper sulphate and sulfuric acid. When you dilute you will also be lowering the sulfuric acid which will need to be increased to the suggested level. Thus you will need to lower the SG to a level well below the saturation level particularly as you have tanks that are increasing in copper content. It is really necessary to do an analysis to know where your copper and sulfuric are either before or after dilution or you are really in the dark. What will happen with plating is that the copper will increase and the sulfuric acid decrease, so regular additions of sulfuric acid should be made and no copper sulphate.

A. I hope that you mean half a gram of murexide [affil links]-salt indicator. I find that you need to play with endpoints for the different indicators. You might try a normal titration. Then try one with 0.1 grams of indicator to a faint end point. Add another 0.1g to the same solution. If you over shoot, add 1 drop of the copper solution and continue the titration. You can go back and forth several times on the same sample. Keep titrating until you have made enough runs to be at a 1.0 gram of murexide indicator. Will have to look at my books tonight. I thought that a "Starch-iodine" endpoint was the normal analysis for copper.

A. While I agree with the advice re the analysis technique perhaps Hazel should be looking at other causes for her soft copper problem rather than copper metal concentration.

A. I agree with Geoff, you need to check the additive concentration and feed system if applicable. The copper content of the bath will have minimal impact on deposit hardness.

A. In most cases murexide is used in only titrations pertaining to electroless solutions. I use sodium thiosulphate as the titrant. The procedure is as follows, 5ml Cu solution, 100ml D.I. H20, 2ml NH4OH, heat to a boil for 15 min,remove from heat add 10 ml acetic acid ⇦ this on eBay or Amazon [affil links] ,cool solution add 25 ml potassium iodide,titrate with sodium thiosulphate to a pail yellow,add 1.00g starch indicator solution will turn grey,continue titrating with thiosulphate until white end point(ml thiosulphate)1.336 will give you grams per liter of Cu.Hope this is what you were looking for.

A. Fix the titrator.

A. I, too, would get the titrator fixed ('cause you can use it for a lot of other things), but an ion specific electrode method would work.

A. Hi neighbor, well one option is to use a outside lab that is close to you..

A. This procedure for the gravimetric determination of Cl- in CuSO4 baths is lifted from "Analysis of Electroplating and Related Solutions" [on AbeBooks or eBay or Amazon affil links] by Langford/Parker:

Pipette [pipettes on eBay or Amazon [affil links] 100 ml of solution into a 500 ml beaker [beakers on eBay or Amazon [affil links] . Add 5 ml conc. HNO3 and 10 ml 0.1N KMnO4 solution. Stir, then add 15 ml 0.1 N AgNO3 solution. Boil until the AgCl is completely coagulated, filter through a tared sintered glass crucible, wash well with 2% HNO3, then dry at 110 °C and reweigh.

Wt AgCl (in grams) X 2.474 = g/l Cl- in bath.

(My note: a Gooch crucible fitted with a fiberglass filter mat would likely work too).

Hope this is of some help.

A. Do an internet search for the Fajan's method. It has numerous advantages over the gravimetric method or an ISE method.

Hi Gaura. As you see, we appended your inquiry to an earlier thread which addresses it. But please feel free to expand upon your question if this didn't answer it for you though. Good luck.

Regards,

A. Tyrone,
With metallic impurities, at least you know how to conduct an analysis because you know what you are looking for. Say Pb, Fe, Zn. Even organic chemists (which not many pc board shops can afford to hire) have fits because they don't know what type of organic contamination to start to look for. I am not familiar with HPLC, is it a logic controller? Good copper suppliers will do elongation and ductility tests for customers. They also can tell by these tests if the bath needs carbon treatment. I like to run carbon packs in the filter system once every two months, and batch carbon/ hot peroxide treat once per year. Good Luck!

A. It is similar to HPLC, but look into Ion Chromatography. Dionex used to be the major player in this field as applied to electroplating. Take a look at their web site for a better idea.

A. Before getting involved in very expensive analytical techniques, you should ask what you want the information for and what you will do with the result.
I suggest that what you are trying to establish is whether the carbon treatment is effective or not.
This is cheap and simple.
You only need to run a Hull cell test before and after treatment. The result should be very obvious.
You can save even more time and energy by carbon treating a small sample before working on the whole bath.
Remember; some organics have to be oxidised with peroxide before carbon treatment and not all organics (low molecular weight) are removed by carbon. If treating a sample of the bath is not effective, it may be more economic to change the bath.
It is also worth checking that your carbon is a suitable active grade and not too old.

A. Tyrone
OK if you want to go that route, I suggest that HPLC will show the presence, and to some extent the quantity, of organics but will not identify them. Polarography is better.
You should be looking at solvent extraction followed by Infrared spectrometry, or GLC with a mass spectrometer.
In any case, you need to start by analysis of any brightener system that you are using.
This is serious chemistry. Try talking to your local university.
Please share any results.

A. I have some years experience in analysing plating baths and their organic contents. Analytical techniques are very good once you know what you are looking for. Both HPLC and IC are expensive and sophisticated pieces of analytical equipment; both require skill to operate and to analyse the results. Furthermore, you need to know what type of detector to use so you can identify the various organics. I suggest you talk to your chemical supply house and ask them for advice, as they will know what organics could and should be in the bath. You may even be able to get them to do the analyses for you.

A. I ran HPLC and HPLC-MS for 8 years. The results that you will get will tell you nothing unless you have a standard for that "organic" material.
The manufacturer of your plating solution is your best source of help. If you are using a home brew, you will soon find out why a proprietary from a reputable company is money well spent.

A. I would suggest you purchase a book with the information on solution analysis. If not, try to get a copy (new or old) of the Metal Finishing Magazine Guide Book Edition.

If you are using a proprietary bath (and to get best results you should) ask your supplier for the analytical instructions.

A. Add Reagent Grade H2SO4 and 10% KI. Titrate with Sodium Thiosulphate and use a starch indicator to help you see the endpoint. It'll turn a creamy white when it's done. I'll leave all the math up to you. Good Luck!
As for the acid part, a simple acid/base titration with NaOH would be fine.

A. To analyse for sulfuric Acid content:10ml sample diluted to 50 mls with de-ionised water. Add 5 drops of methyl orange ⇦ this on eBay or Amazon [affil links] indicator and titrate with 1.0N Sodium Hydroxide solution to a pale-green end-point. Calculation is Titre mls x 4.9 = g/l free sulfuric Acid
For Copper: Try taking a 5ml sample, dilute to 100 mls with de-ionised water. Add 5 mls of 50% Ammonium Hydroxide solution (solution will go deep-blue due to the formation of cuprammonium ions), add about 2 gms of Sodium Fluoride - to hold up any iron then make just acidic with 50% acetic acid solution. Add 2-3 gms of Potassium Iodide, mix then add a few mls of 1% starch indicator. Titrate with 0.1N sodium thiosulphate ⇦ this on eBay or Amazon [affil links] solution to a chalky-white end-point.
Calculations: Titre mls x 1.272 x 3.927 = g/l copper sulphate as copper sulphate pentahydrate.
Hope this info helps you and best wishes for 2009!

A. Hi Ajit,

It doesn't make sense that sulfuric acid content in acid copper bath can be directly revealed by conductivity meter as anions like sulphate, chloride and cations like sodium, copper, etc., also contribute conductance. Hence higher conductivity does not necessarily imply a higher sulfuric acid concentration.

You may analyze sulfuric acid content by acid base titration.

Regards,
David

A. Hi Ajit
I agree with David. Conductivity is not going to help.
If you want a rapid analysis of a standard copper sulphate bath here is how.
Titrate with alkali to first precipitate - the copper provides its own indicator. Time about 2 minutes.
Measure the density with a hydrometer, about 1 minute.
The copper content is obtained from published tables or make up standard solutions to cover the expected range and draw your own graph.
Not as accurate as a full formal analysis but fast and good enough as this bath works within wide limits.

A. Hello David. We have now merged together our various threads on analysis of acid copper plating baths, and appended your inquiry to it. I believe it addresses them all, but if you have remaining questions, please advise. Thanks.

Regards,