metal fill inside inductor

I am designing an on-chip inductor. To satisfy the metal local density rule, I need to put many small metal squares inside the inductor loop. Anyone know how much it will degrade the performance of the inductor? Will Q and L change a lot? What is the best way to place the metal squares? Thanks.

A small metal inside of an inductor loop will decrease slightly the inductance of that inductor.
From the formula Q = (ω*L)/R, lower inductance means lower Q.

metal filled inside inductor will destroy your design because the inductor model is based on no metal fill. you can simulation in ASD's momentum for your condition.

The vaste metals can not be put at the center or around of an inductor.These will increase eddy currents to substrate and decrease Q factor and shifts indcutor value from calculated one..

The inductance will not be effected - it is magnetical property and floating
metals not effect in any way on Mu_r.
Commonly Q degrade a little bit due to chnage in Effective E_r of surrounding.
Dummies better to put outside the inductor.

Regards,

Gosha

When I was 11 years old I built my first Superhet radio. Then, I’ve learn that putting different types of metals inside of the LO inductor, the tuning frequency is changing more or less.
The reason is because the inductance is changing.

It's about time to try again .
But this time be sure the metals are has Mu_r = 1 as in metals on chip such as gold,copper,alumnium (They have Mu_r very close to 1).

Probably in your childhood you used Iron which have Mu_r = 4000 or some
other metal with Mu_r > 1 these metals can store energy induced by magnetic
fields.

There is pretty much equivalence in this matter to E_r.
E_r - is storage of energy in molecules which organized in dipole due to electric field

Mu_r - is storage of energy by tiny magnetic dipoles in material induced by magnetic field.

Magnets for instance has permanent magnetic dipoles, unlike Iron
which magnetic dipoles induced by external field vanish as a times goes
due to thermal activity.


By the way, frequency shift could be also changed by inserting the metals even with
Mu_r=1.
Significant freq change can be due to floating metals,when they significally change the effective dielectric therefore the capacitance is changed which force frequency
to shift - but again the shift is due capacity not inductance change.

This why I stated before that Q changes and not the L.



Regads ,


Gosha

I’ve tried then, I try now and I would try in the future this experiment.
The result that I get is the same regardless what some people post on this forum.

One of the duties of the metal detectors (manufactured during decades) is to detect buried metals, especially gold.
If gold is not affecting the inductance of the inductor (part of the front-end resonant circuit) hundreds of thousands of people waste their time for nothing.

On the other hand the topic of this post is about: if metal inside of an inductor affect the inductance. The answer is YES

Inductor metal core material by it's permeability changes the inductance of a coil. Materials with relative permeability greater than 1 increase inductance. Materials such as aluminium and brass has relative permeability smaller than 1 and they decrease coil inductance. This core materials are used tuning and for frequencies higher than 30MHz.