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topic 23826

Determining Phosphorous Content in Electroless Nickel Plating

A discussion started in 2003 but continuing through 2020


Q. We electroless nickel plate 15 mm dia., 100 mm long pins. I wish to know method/s to determine phosphorous content in the plated layer. coating thickness is about 10 - 15 microns.
The component is further baked to increase coating hardness to 65 HRc.

Expert advice will be highly appreciated.

electroplating jobshop - CHANDIGARH, CHANDIGARH, INDIA


A. It is controlled by temp, pH.

- Korea


A. There are two basic methods to determine P in EN. One is atomic absorption spectrophotometry, the other, less accurate is by density (mass per volume). EN with 10% Phos weights approx. 7.8 grams/cubic centimeter, whereas 4%P weights 8.4 (linear function).

Guillermo Marrufo
Monterrey, NL, Mexico


Q. Thanks for the practical info, Guillermo, which I would like to follow up: is there a strip and analyze method? That is, does anyone strip the coating off and then determine how much phosphorous vs. how much nickel is dissolved in the stripper?

Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha


A. Thanks for the follow up, Ted. The older I get, the more I tend to accept that there are always other alternatives. I can't see why your idea couldn't be possible.

Guillermo Marrufo
Monterrey, NL, Mexico


A. Ted had asked about a strip and analyze procedure. Occasionally, we perform a procedure that is just that. 1) Plate a pre-weighed stainless coupon.

2) Strip in nitric and determine weight loss. (total weight of coating)

3) Analyze Phosphorous (phosphate) in solution similar to method 39.02 in "Colorimetric Analysis of Metal Finishing.." by Knowles. Calibration curve is necessary.

4)Use simple math to determine %P by weight.

The procedure is time consuming compared to an AA method, but it is accurate and precise and may be used if an AA is not readily available.

Jon Barrows
Jon Barrows, MSF, EHSSC
Springfield, Missouri


Hey, thanks Jon.

Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha


A. Vikram,

The method of X-ray fluorescence will allow you to measure both the thickness of the NiP deposit and the %P present in it. You should investigate this method. It is non contact and non destructive and typical analysis time is less than 1 minute.

Chris Horvath
- Elk Grove Village, Illinois, USA


Q. Dear Mr. Chris Horvath,

I tried exploring the method of X-ray fluorescence, but the results said nickel phos which is not possible as we do get a hardness of 66-67 Hrc after heat treatment and its an established formulation.

Can you throw some light on how exactly we should go about it , maybe we took the wrong turn.

Thanks in advance



A. Have you tried or considered the X-ray fluorescence method to analyze %P and thickness of NiP/Fe?


Not every XRF system is capable of doing this function. You must make sure that the one you are using has the correct hardware and software. If you already own a system then I suggest you contact the manufacturer to see if they offer this feature. If not, you may want to look around at some others that do. If you borrowed time on someone else's system, check with them to see if they purchased this feature. We have seen excellent results for this application compared to AA and ICP analysis when done correctly.

Chris Horvath
- Elk Grove Village, Illinois, USA


A. One relatively simple non-destructive test available on small parts or pieces is the EDS analysis under an electron microscope (SEM). Many SEM equipment have the attachment. A physics or chemistry dept at a nearby university should have it. The results will be within 1%. Make sure the surface is clean because it will read what's there.

Mandar Sunthankar
- Fort Collins, Colorado


We had an analysis sent for SEM-EDS at one time, thinking that it was the most accurate method. As it turned out, the SEM analyst said that this determination is only semi-quantitative. He was only willing to put it at ± 10%. He explained why it was not more precise, but I have forgotten the reasoning. When I heard that, I no longer considered it to be worth the $'s. If SEM-EDS is really ± 1%, then it may be a different story depending on the analysis price.

Jon Barrows
Jon Barrows, MSF, EHSSC
Springfield, Missouri


A. Jon, for better accuracy of measurement, the lab needs better (proper) software and equipment calibration and, expertise in how to read the analysis. It should not cost more that $50-100 for a sample that includes SEM and EDS. I have frequently used EDS analysis in last 20 years. It is reliable for atomic numbers above 12 or so.

Mandar Sunthankar
- Fort Collins, Colorado


A. I thought I'd try to clear up a few points about SEM/EDS analysis. SEM/EDS micro-analysis is easily capable of ± 5% relative accuracy for concentrations of 5.0% P in Ni if standards are used. In other words the phosphorus concentration would fall between 5.25 and 4.75%. These results may be as good as ± 2.0% relative error. Using "standard-less" analysis relative error would be between 5 and 10% relative error. So at worst we would be looking at a spread of between %5.5 and 4.5% P in Ni.

Other factors affecting the analysis would be surface roughness, whether standards were used in the analysis and instrumental conditions, and, most importantly, the homogeneity of the layer to be analyzed. Beam penetration into the sample is generally in the order of 1 micrometer and areas for analysis may vary from a single micrometer up to 100s of square micrometers. These systems also have capability of imaging elemental distributions on a surface which may be useful in determining variations of P distribution in the Ni coating.

Neil Rowlands
microanalysis - Concord, Massachusetts


Q. We are plating electroless nickel on nylon surfaces. What is the best way to determine the phosphorus content of the plating? We can not simply strip off the nickel with nitric acid because it dissolves the nylon also.

Daniel Ostermayer
University Research - Scranton, Pennsylvania


Q. I want to analyse BY AAS (atomic absorption spectrometry) the phosphorous content my EN. How can I do that?

semiconductors - Bromont, Quebec, Canada

November 3, 2010

Q. Dear all,

I would like to know if there is a fast and cheap method (like treatment with some acid, or heat treatment, etc) to find out if P is present in EN? Some of the deliveries are not NiP plated and some of them are...that's why it is big problem for us.
I know that there are many quantitative methods of determining P% in the layer, discussed in other inquiries (EDS, spectroscopy etc), but it takes long time to send it outside the company and have it checked (no equipment available in house).

Thanks for all comments

Lukasz Jarosz
product designer - Nordborg, Denmark

November 4, 2010

A. This simplest and cheapest way that I can think of is to follow the basic method 39.02 in "Colorimetric Analysis of Metal Finishing.." by Knowles, but you can simplify it to a qualitative test by just checking for a visual change to yellow which would indicate that phosphate is present in the stripping solution. You wouldn't need to purchase anything except for a few chemicals and some glassware.

Jon Barrows
Jon Barrows, MSF, EHSSC
Springfield, Missouri

simultaneous November 5, 2010

A. Dear Lukasz Jarosz,

Even simpler:
Take as reference a P-containing and a non P-containing sample
Put them in an air recirculating furnace at 500° C - for 3 minutes.
Look at the difference.
After that, test your unknown samples and always together with some known references.

Good luck,


Harry van der Zanden
Harry van der Zanden
- Budapest, Hungary

November 5, 2010

A. If you have EN, you will have either phosphorous or boron in the plate as they are the two (possibly only) reducing agents used. Boron is a lot harder and more expensive, so you have a 99% probably of it being P. That said, Mid P is easier and cheaper than low or high P, so unless you are paying a premium price, you will have a 4-7 % P content.

James Watts
- Navarre, Florida

October 28, 2011

Q. If I specify EN per ASTM B733, Type I, do I automatically get about 5-9% of Phosphorus? ASTM B733-97, Fig X4.1 seem to indicate so. Could I be possibly getting some % of Boron rather than Phosphorus, if I specify Type I? Does Boron provide similar electrical properties as Phosphorus - such as solderability, bondability, increase in conductivity, etc. in EN?

Juliet Lee
Mechanical Engineering - South Setauket, New York, USA

October 28, 2011

Hi, Juliet.

Can you please try to describe your own situation a bit rather than phrasing your question with abstract "Ifs"? We've learned from posting tens of thousands of questions here that people are very reluctant to comment when they don't know what situation they are commenting on ... probably afraid of responding, then seeing "Aha! My vendor is in trouble now that I've got your statement" :-)


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

April 23, 2013

Q. I would like to know the P% testing method through chemical dissolving method on ELECTROLESS NICKEL PLATING.

RFQ: Is there anybody to check the above requirements in Chennai or Bangalore?

With regards,

- Chennai, India

May 20, 2016

Q. % of P in NiPB deposit can be evaluated by using XRF instrument.I am frequently using this instrument...
... But my question is how to calculate Boron content in alloy deposit and how to increase hardness of NiPB coating. Still I am facing issue regarding hardness in NiPB coating. I am looking forward for your valuable suggestions.
Thank you

Nisha Katiyar
- Bangalore, Karnatka, and India

February 15, 2017

A. Newer XRF instruments with Silicon Drift Detector (SDD) should in most cases be capable of determining the P% content of EN coatings quite accurately if Calibration Standards are used for setting up the application in the relevant P% intervals.

However make sure that the X-ray tube used is suited for the application. Furthermore the coating to be measured should be the top coating since the signal from P in an intermediate coatings will easily be shadowed by a top coating

P. Westermann
Academic Materials Research Centre - Copenhagen, Denmark

Electroless Nickel XRF App calibration

February 12, 2020

Q. Hello,
Jobshop here looking for some guidance on how other shops calibrate their NiP applications on XRF machines.

We only operate one kind of mid-phos electroless nickel bath and currently use PURE Ni Foils with a "calculated" 7% NiP thickness and set them as 7% in our calibration on the machine. The normal apps we use then are set to output readings at an assumed 7% P.

One of our XRF machines is capable of measuring P content though and we also have a set of hard NiP-Fe standards that we have a NiP-Fe application calibrated with.
The same machine will only accept foils with an identical %P content for calibrating the other NiP-Al/Brass/Cu-Fe/Fe etc applications that are printing results at an assumed 7%.

We have not been able to find a supplier that can furnish foils at exactly the same phos content so we've only used the pure Ni foils with the calculated 7% P thickness.

We were always told this is how other shops do it from the XRF manufacturer but I've never been in contact with another XRF operator to ask, is this what most people do?

Just to illustrate our situation better:
We have multiple pure Nickel foils labeled normally as nickel foils, we have 2 pure Nickel foils that are only labeled as calculated "7% NiP" thicknesses, and then we have a set of hard NiP over Fe standards that have varying phos content between 2 and 15% and varying thicknesses


Ben Jacobson
- New Jersey, USA

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