Magnetic MLCC vs. Non Magnetic

[kurtak]

I got a PM asking me the following --- “Is there any chance of PMs being in the magnetic ones at all”

There are no PMs in the magnetic ones - MLCC's are ether NME (Noble Metal Electrode) with Ag/Pd as the noble metals used

Or - BME (Base Metal Electrode) with Ni/Cu used as the base metals

Though they still make NME's they started making BME's in the mid to late 1990s due to the high cost of noble metals

There are two classes of MLCCs --- Class 1 - & Class 2 --- before the change to BMEs in the 90s both classes where made with NME --- now (after the change in the 90s) Class 1 are still made with NME & Class 2 are made with BME

The change from NME to BME of course changes the electrical properties of the capacitor – but it is/was found that for the applications where Class 2 capacitors are used BME’s are expectable – so to save on cost BME’s are what they now use if the application calls for Class 2 capacitors --- when the application calls for Class 1 capacitors – NME’s are still used

The “only” PMs that “might” be associated with magnetic MLCCs is – IF - silver bearing solder is used to solder them to the board --- if memory serves me right – the silver in silver “bearing” solder runs “about” 3% --- that means 3% of the solder “only” – not 3% of the MLCCs – the silver associated with the MLCCs would therefore be FAR less --- certainly not worth chasing

Bottom line --- remove the magnetic MLCCs with a magnet & toss them – they have little or NO value

Personally – I just toss them in with my brown boards (along with anything & everything of non PM value that comes from depopulating boards) so I get at least brown board value for all my non PM components that come “off” boards when depopulating them

Kurt

 

[chuckgambale]

Excellent post Kurt

 

[anachronism]

There is one addition to this excellent post if I may.

Be careful as to how you test for them being magnetic. A slight magnetism when you use a Neodymium magnet does not necessarily mean it's a base metal MLC because there can be magnetism due to nickel on the connectors.

Use an old fashioned normal magnet to test them.

 

[g_axelsson]

There is one addition to this excellent post if I may.

Be careful as to how you test for them being magnetic. A slight magnetism when you use a Neodymium magnet does not necessarily mean it's a base metal MLC because there can be magnetism due to nickel on the connectors.

Use an old fashioned normal magnet to test them.

Second that!

The end caps can be protected by a nickel diffusion barrier, much like gold plating isn't made directly on copper traces but with a thin nickel layer first.

Easy test, crush a sample and leach.

Göran

 

[kurtak]

There is one addition to this excellent post if I may.

Be careful as to how you test for them being magnetic. A slight magnetism when you use a Neodymium magnet does not necessarily mean it's a base metal MLC because there can be magnetism due to nickel on the connectors.

Use an old fashioned normal magnet to test them.

Second that!

The end caps can be protected by a nickel diffusion barrier, much like gold plating isn't made directly on copper traces but with a thin nickel layer first.

Easy test, crush a sample and leach.

Göran

I like using the round donut magnets that come out of microwaves - they are not so strong that they pick up Ni plating

Kurt