Hi all,
Well ... I have been working for some time now on a 6 layer DAC PCB that I am just about to send off for manufacturing (JLCPCB) - and then I notice that the only surface finish JLCPCB has available for 6 layer PCBs is an ENIG finish, which means a layering of nickel subsequently covered with gold.
And remembering that e.g. WBT (the German connector company) and others over time have been critical of nickel as a sublayer in e.g. connectors I was wondering if there is a current view on nickel's sound imprint?
Cheers & thanks for any insights on this 😉
Jesper
Well ... I have been working for some time now on a 6 layer DAC PCB that I am just about to send off for manufacturing (JLCPCB) - and then I notice that the only surface finish JLCPCB has available for 6 layer PCBs is an ENIG finish, which means a layering of nickel subsequently covered with gold.
And remembering that e.g. WBT (the German connector company) and others over time have been critical of nickel as a sublayer in e.g. connectors I was wondering if there is a current view on nickel's sound imprint?
Cheers & thanks for any insights on this 😉
Jesper
My two cents... nothing to worry about. Unless you start using 100% silver solder everywhere, then we could talk. 🙂
In the 1980’s, I worked for Western Electric (AT&T’s equipment manufacturing division at that time). This was back when AT&T, essentially, built the entire telecommunications network of the U.S., including transoceanic, undersea cable. We plated our own copper parts and connectors that required quality electrical contact. They were plated with gold over top of nickel. That should tell you something about that combination.
There is no sound imprint, despite what you may have heard tell.
There is no sound imprint, despite what you may have heard tell.
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Plating gold over copper has different bad effects longterm. Gold has micropores, and copper will oxidate below over time. Also, trough those same pores, copper will permeate and with air mosture, it will induce galvanic corrosion. Now, all those effects are proportionally less important with increased gold layer thickness. Nickel acts as a buffer layer in between, so there are no effects mentioned, and it also provides another durability layer. There is also several gold platings in the industry, soft and hard. Soft gold plating is as pure as gold can be plating, and it is basically soft and won't handle much scratching. Hard gold plating is with a gold alloy specificaly made for increased hardness when you need a lot of physical contact with other surfaces.
Now for your original question, Viborg for example does stuff differently, they plate copper with copper to even out the surface, then plate with silver, and then with gold. Solid thickness platings so no issues there (and silver is less permeable than gold so it acts as a buffer a bit). Sound wise, only you can see if you hear or percieve the differences in sound (i plate my diy copper bus bars as viborg, but thats just because i can, not sure if nickel would make a difference there since i haven't made on with nickel plating inbetween).
Now for your original question, Viborg for example does stuff differently, they plate copper with copper to even out the surface, then plate with silver, and then with gold. Solid thickness platings so no issues there (and silver is less permeable than gold so it acts as a buffer a bit). Sound wise, only you can see if you hear or percieve the differences in sound (i plate my diy copper bus bars as viborg, but thats just because i can, not sure if nickel would make a difference there since i haven't made on with nickel plating inbetween).
Hi again - & good morning (as it is morning here in Denmark) ...
And then thanks for your feedbacks - and some background into the practicalities and history of copper plating/coating. Hmmm ... I admittedly was hoping that someone had tried out the various connector & plating/coating options from a sound imprint point of view, although it could be challenging to do in practice as I reckon it may require specialized machinery to some extent.
My reason for asking is that years ago I compared some different connectors (including the WBT RCA connectors) and at least to my ears there were quite clear audible differences between the various connectors. The WBTs were in a league of their own and, again to my ears, also better than the gold plated lower cost alternatives I tried (not too many, though). I did, or do, not know what caused these audible differences yet the nickel plating was considered a possible culprit at the time.
Anyway, JLCPCB offers the finishing it offers, and I am reluctant to switch manufacturer right now, so I guess I'll have to find a way to handle this. Again thanks for your feedbacks ;-)
Cheers, Jesper
And then thanks for your feedbacks - and some background into the practicalities and history of copper plating/coating. Hmmm ... I admittedly was hoping that someone had tried out the various connector & plating/coating options from a sound imprint point of view, although it could be challenging to do in practice as I reckon it may require specialized machinery to some extent.
My reason for asking is that years ago I compared some different connectors (including the WBT RCA connectors) and at least to my ears there were quite clear audible differences between the various connectors. The WBTs were in a league of their own and, again to my ears, also better than the gold plated lower cost alternatives I tried (not too many, though). I did, or do, not know what caused these audible differences yet the nickel plating was considered a possible culprit at the time.
Anyway, JLCPCB offers the finishing it offers, and I am reluctant to switch manufacturer right now, so I guess I'll have to find a way to handle this. Again thanks for your feedbacks ;-)
Cheers, Jesper
The thing is, it's not usually about the plating, as much as the quality of the connector itself. If you have a connector that is the same, but with and without nickel plating, then you can make conclusions, otherwise it's not possible to say.
Gold plating on pcbs, nickel and gold will dissolve in your solder. It makes the solder joint liiiiittle bit more brittle, but nothing to be concerned about in our use cases. In aero and space, yes, plating used there is usually removed before soldering.
Gold plating on pcbs, nickel and gold will dissolve in your solder. It makes the solder joint liiiiittle bit more brittle, but nothing to be concerned about in our use cases. In aero and space, yes, plating used there is usually removed before soldering.
@Brijac :
@analog_sa : Well ... old, prejudiced geezers are also welcome to chime in ;-) ... Thanks for your feedback.
The only thing is that in this context (6-layer board) JLCPCB does not offer any other finishes so I probably will have to think about a workaround for this
.. And converting the layout to a 4 layer board just is not an option due to complexity ...
Slightly less "cheers/cheerful",
Jesper
Yes, I am aware of this ... but there is only so many things I have time - and equipment for that matter - to try out. And trying out identical connectors with and without nickel is not something I will be able to do. From reading your posts I am BTW thinking if you have your own plating facility? Sounds attractive 😉
@analog_sa : Well ... old, prejudiced geezers are also welcome to chime in ;-) ... Thanks for your feedback.
The only thing is that in this context (6-layer board) JLCPCB does not offer any other finishes so I probably will have to think about a workaround for this
.. And converting the layout to a 4 layer board just is not an option due to complexity ...Slightly less "cheers/cheerful",
Jesper
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I don't believe in different sound quality of different metals, and not even in the sound quality of different metal layers on top of each other. A metal is a metal is a conductor and has pure ohmic resistance. And pure ohms do not influence but quality.
But I think I know where this idea comes from.
If you connect (not plate, but connect as press or screw one metal to another) you do not have a metallic connection. Air is also part of the connection surface. Air binds with metals and from oxides. And there you have it, metal oxides may possess semiconductor properties. Copper is notorious, and I believe Selenium as well. In the past we had Copper Oxide and Selenium Oxide rectifiers.
Contact surfaces with semiconductor particles included form tiny little diodes and those cause nonlinearities in the conductor chain. And that is bad.
Some materials like Silicium when containing certain impurities which is diffused onto another piece with different impurities might also form a non-linear junction. It also called a diode. But remember, Silicium is a metalloid not a metal.
I think it is safe to assume that a metallic connection, like plating or soldering where no oxygen can creep between the two metals, is a safe and purely ohmic connection.
Obviously there are metals which are not suited for plating on top of each other. Chrome on steel doesn't work, therefor it is steel - brass - chrome. The same goes for gold on copper. It needs nickel in between. As @Brijac stated, gold is permeable and could cause copper to oxidize, which is unacceptable. Also because of the semiconductive properties of copper oxide.
Industry has learned that, and this is nicely explained by @Ken Newton.
One note on Copper Oxide. It has semiconductive properties, but it is a bad semiconductor. Therefor it is not used as such. Still it is "good" enough to cause harm by causing unwanted rectification in a junction.
But I think I know where this idea comes from.
If you connect (not plate, but connect as press or screw one metal to another) you do not have a metallic connection. Air is also part of the connection surface. Air binds with metals and from oxides. And there you have it, metal oxides may possess semiconductor properties. Copper is notorious, and I believe Selenium as well. In the past we had Copper Oxide and Selenium Oxide rectifiers.
Contact surfaces with semiconductor particles included form tiny little diodes and those cause nonlinearities in the conductor chain. And that is bad.
Some materials like Silicium when containing certain impurities which is diffused onto another piece with different impurities might also form a non-linear junction. It also called a diode. But remember, Silicium is a metalloid not a metal.
I think it is safe to assume that a metallic connection, like plating or soldering where no oxygen can creep between the two metals, is a safe and purely ohmic connection.
Obviously there are metals which are not suited for plating on top of each other. Chrome on steel doesn't work, therefor it is steel - brass - chrome. The same goes for gold on copper. It needs nickel in between. As @Brijac stated, gold is permeable and could cause copper to oxidize, which is unacceptable. Also because of the semiconductive properties of copper oxide.
Industry has learned that, and this is nicely explained by @Ken Newton.
One note on Copper Oxide. It has semiconductive properties, but it is a bad semiconductor. Therefor it is not used as such. Still it is "good" enough to cause harm by causing unwanted rectification in a junction.
There are always ways.... you could off-load the analog section to a 4-layer PCB with HASL (leaded or lead-free) finish. Ideally you also make ENIG ones and perform a blind test. The outcome of which would be quite predictible, me thinks ;-)
The performance and sound of a DAC is much more depending on other stuff (Vref, clocks, etc, and of course layout) than PCB surface finish and/or solder type.
Nickel might become problematic with very high current densities because of its ferro-magnetic properties. For a DAC, most likely totally negligible.
I second the motion to do blind testing. Once you've read that WBT (or whoever) is critical (or claims to hear a difference) you are much more likely to "hear" a difference yourself (expectation bias).
Member
Joined 2006
Some facts here:
1) copper surface can be easily oxidized when exposed to air.. and the oxide layer not only has poor conductivity, it is semiconducting, which produces rectifing effects... (in early days, copper oxide was used in producing rectifiers.)
2) When gold is deposited directly onto copper surface... copper atoms will diffuse into the gold layer, one could notice the change of the gold surface color in time.
3) Nickel, as an adhesion layer and diffusion barrier, is thus often applied to plate over to copper first before a gold layer is deposited on top.. Nickel is fereomagnetic..
1) copper surface can be easily oxidized when exposed to air.. and the oxide layer not only has poor conductivity, it is semiconducting, which produces rectifing effects... (in early days, copper oxide was used in producing rectifiers.)
2) When gold is deposited directly onto copper surface... copper atoms will diffuse into the gold layer, one could notice the change of the gold surface color in time.
3) Nickel, as an adhesion layer and diffusion barrier, is thus often applied to plate over to copper first before a gold layer is deposited on top.. Nickel is fereomagnetic..
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I think Nickel is widely used in electroplating as an intermediate, with a reason (AFAIR it creates a very even surface and behaves very well).
Also you might want to ask yourself: If literally everybody is doing this plating, why shouldn't I?
I only see advantages in going for gold.
Also you might want to ask yourself: If literally everybody is doing this plating, why shouldn't I?
I only see advantages in going for gold.
This is where it makes sense to use connections that are rated "gas-tight", but this is more for wire terminations rather than PCB terminations. Gold-plated electrical contacts don't have any oxidation issues unless the gold plating is poor quality or too thin (and try to use gold-against-gold only, preferably not gold-against-nickel and never gold-against-tin).
IDC, cage clamp, and many types of well-engineered screw terminals will allow gas-tight connections.
Another way of saying it: if you can't achieve a gas-tight connection, best to use gold-against-gold or nickel-against-nickel depending on the circuit characteristics.
Also here:
https://workmanship.nasa.gov/lib/insp/2 books/links/sections/601 General Requirements.html
Gold plated surfaces that will become part of the finished solder connection shall be tinned prior to soldering to remove the gold plating.
NASA-STD-8739.3 [7.2.5.c],[13.6.2.a.3]
https://workmanship.nasa.gov/lib/insp/2 books/links/sections/601 General Requirements.html
UNACCEPTABLE
GOLD PLATING
GOLD PLATING
Gold plated surfaces that will become part of the finished solder connection shall be tinned prior to soldering to remove the gold plating.
NASA-STD-8739.3 [7.2.5.c],[13.6.2.a.3]
Yeah, sure. I certainly hope, you follow these standards by the word. I wonder why the industry finds it acceptable, not to sleeve every 1N4148 on their PCB, even if it's a million dollar device.
Hi all & thanks for your varied and informative replies ...
However, to be honest I am not at this point in time looking to delve deeper into the chemical / theoretical aspects of plating, but more trying to find out if someone had actually listened to (and maybe found, in a feasible way) a SQ difference with and/or without nickel e.g. on connectors. This as a means of assessing what would happen SQ-wise with a PCB covered with a nickel + gold finish (ENIG) - "everything else being equal" - to an extent reasonably possible.
And apart from analog_sa's observations regarding nickel plated connectors I do not read in your replies a feedback on the potential SQ difference between with / without nickel ... ? Which is fine - I notice there is much other good information in your replies. But in this context I was looking for some SQ/listening experiences ... and thus, unless someone has some SQ experiences, I will personally let the subject be for now.
That said, as most always in this forum, I would like to thank you for your helpfulness and willingness to reply - appreciated! And then also take the opportunity to wish everyone a Merry Christmas - with whichever meaning/significance Christmas may have for each of you ...
Cheers & thanks,
Jesper
However, to be honest I am not at this point in time looking to delve deeper into the chemical / theoretical aspects of plating, but more trying to find out if someone had actually listened to (and maybe found, in a feasible way) a SQ difference with and/or without nickel e.g. on connectors. This as a means of assessing what would happen SQ-wise with a PCB covered with a nickel + gold finish (ENIG) - "everything else being equal" - to an extent reasonably possible.
And apart from analog_sa's observations regarding nickel plated connectors I do not read in your replies a feedback on the potential SQ difference between with / without nickel ... ? Which is fine - I notice there is much other good information in your replies. But in this context I was looking for some SQ/listening experiences ... and thus, unless someone has some SQ experiences, I will personally let the subject be for now.
That said, as most always in this forum, I would like to thank you for your helpfulness and willingness to reply - appreciated! And then also take the opportunity to wish everyone a Merry Christmas - with whichever meaning/significance Christmas may have for each of you ...
Cheers & thanks,
Jesper