Hi Guys , new to the forum joined a few days ago and i have been hooked since. Lots of great info on here. Little background about me. I work for a computer recycler for the past 4-5 years now. An im sorry to say its taken me this long to finally pursue my curiosity. My question is not actually for me Its for my boss an these boards that came in. He thinks there is gold on them i am not so sure. I brought in an acid tester i had at home but i am not sure if this is even a viable way to test this type of stuff. The acid did not eat away at the metal so it would lead me to believe it maybe is but i dont want to tell him yes an then he sells them only to find out its not and pays to ship etc. It is hard to tell in the pictures but the color does not really look like gold it looks more like copper or a rose gold color that is my concern and why i have doubts. Thanks in advance for an info. Joe
New here saying hi an have a question about some boards i ha
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etack
Well-known member
the gold is gold plate.
it is thickest on the fingers. the other is flash plated.
welcome to the forum read before you ask. nothing is new on the forum.
Eric
it is thickest on the fingers. the other is flash plated.
welcome to the forum read before you ask. nothing is new on the forum.
Eric
Oh i have not stopped reading since i found this site lol. Its just tough sometimes when you dont know exactly what it is you are trying to look up. I will try an look up the flash plating an see what i can learn. But it is safe to say this is gold? Joe
If it looks like copper, it is most probably copper. If it looks like gold, it is most probably gold. The photos look like copper.
compare the color of the board, to gold plated fingers on a memory card.
Also you can try and scrape the surface of the traces, on gold plated circuit boards, you can scrape off the very thin layer of gold and see the copper color underneath, if it is of the same color but only unoxidized copper then they are not gold plated.
The circuit board in your picture looks to me that it may be new blanks before they were plated, I cannot tell from the picture.
Also you can try and scrape the surface of the traces, on gold plated circuit boards, you can scrape off the very thin layer of gold and see the copper color underneath, if it is of the same color but only unoxidized copper then they are not gold plated.
The circuit board in your picture looks to me that it may be new blanks before they were plated, I cannot tell from the picture.
Thanks guys . Yes i am very sketical that it is gold. It does not look like gold at all to me. What threw me off was using the acid to test it. I figured if it wasnt gold it would eat away at the metal? But yes they are new boards. So i think you are correct in saying they probably have just not been plated yet.
darshevo
Well-known member
not the most scientific method, but you could clip a couple of the finger sample off and drop in a small run of AP to see what the result was as well.
How does your test acid react on an old copper penny (not the new zinc penny that even vinegar can dissolve the center out of).
What is your test acid, how is it made?
Copper is very close to the bottom of the reactivity list of metals just above the noble metals and is not reactive to most acids like HCl, being below hydrogen in the reactivity series.
Also test acids have a lifespan, or shelf life (oxidizers can deplete in solution).
What is your test acid, how is it made?
Copper is very close to the bottom of the reactivity list of metals just above the noble metals and is not reactive to most acids like HCl, being below hydrogen in the reactivity series.
Also test acids have a lifespan, or shelf life (oxidizers can deplete in solution).
My guess is that the boards are gold plated by a process that is called ENIG (Electroless Nickel Immersion Gold). It is used for protecting the boards against corrosion before soldering.
ENIG gold is deposited by dipping the nickel plated board first into a nickel solution and then into a gold solution where gold is cementing out on the surface. As the nickel gets covered by gold the process stops by itself when there is a sufficient covering of gold, usually between 0.075 and 0.125 um (3-5 micro inch).
There is no common cathode connection on the fingers at the side of the board so I suspect that they also is only covered with immersion gold. To get a thicker plate you need to connect them together and contact them in a plating bath but I can't see any proof of that.
http://sprg.ssl.berkeley.edu/sprite/sharris/IPC/IPC-4552-Draft.pdf
If you have access to nitric acid, make a scratch on the metallic surface and put a drop there. If it is gold then the acid will work it's way under the plate and it will flake off when the copper is dissolved.
If it is ENIG, then it is easy to calculate the amount of gold on the boards, just calculate the total area exposed (probably no gold under the green solder mask), multiply by the thickness above and the specific weigh of gold. Then decide if it is worth the time and chemicals.
Let us know what you find out, if it is gold or not.
/Göran
ENIG gold is deposited by dipping the nickel plated board first into a nickel solution and then into a gold solution where gold is cementing out on the surface. As the nickel gets covered by gold the process stops by itself when there is a sufficient covering of gold, usually between 0.075 and 0.125 um (3-5 micro inch).
There is no common cathode connection on the fingers at the side of the board so I suspect that they also is only covered with immersion gold. To get a thicker plate you need to connect them together and contact them in a plating bath but I can't see any proof of that.
http://sprg.ssl.berkeley.edu/sprite/sharris/IPC/IPC-4552-Draft.pdf
If you have access to nitric acid, make a scratch on the metallic surface and put a drop there. If it is gold then the acid will work it's way under the plate and it will flake off when the copper is dissolved.
If it is ENIG, then it is easy to calculate the amount of gold on the boards, just calculate the total area exposed (probably no gold under the green solder mask), multiply by the thickness above and the specific weigh of gold. Then decide if it is worth the time and chemicals.
Let us know what you find out, if it is gold or not.
/Göran
Geo
Well-known member
it could be a conformal coating thats removed prior to manufacturing.
