# Design of Spiral inductor(LItz wire) on PCB

1. ## Design of Spiral inductor(LItz wire) on PCB

Hello everyone,

I am working on a project currently where i have to design a spiral circular coil made of litz wire(multiple strands) on PCB.
According to the research that i have been through, it is said that i have to write a matlab script with all the necessary calculations required for the design and then use the matlab file in eagle under extension .ulp to automatically generate the layout.

Now i am done with the matlab srcipt but not sure of using this script in eagle to automatically generate the layout of spiral inductor on PCB.

Do i have to change the script written in matlab compatible to eagle ULP by changing all the syntax ??

It would be of great help if i could get some suggestions

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2. ## Re: Design of Spiral inductor(LItz wire) on PCB

The design principle of litz wire is two-dimensional stranding. How can it be implemented in a planar PCB structure?

If you have an algorithm that generates the PCB structure in Matlab, than you can translate it to ulp language. It has trigonometric functions and the necessary control functions. Or you can write a file describing the structure in Matlab and read it in a more simple ulp program.

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3. ## Re: Design of Spiral inductor(LItz wire) on PCB

Originally Posted by FvM
The design principle of litz wire is two-dimensional stranding. How can it be implemented in a planar PCB structure?

If you have an algorithm that generates the PCB structure in Matlab, than you can translate it to ulp language. It has trigonometric functions and the necessary control functions. Or you can write a file describing the structure in Matlab and read it in a more simple ulp program.

I have written an algorithm in matlab with all the trignometric calculations including formulas to generate the litz wire structure.I am quite new to this ulp pregramming.

So to make this matlab script readable in ulp i have to change the syntax accordingly or write a small ulp program to make it readable ?? (as both the libraries are different)

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4. ## Re: Design of Spiral inductor(LItz wire) on PCB

You can probably refer to existing conversion routines, if you generate a *.dxf file of the geometry in matlab and import it to eagle.

5. ## Re: Design of Spiral inductor(LItz wire) on PCB

Originally Posted by FvM
You can probably refer to existing conversion routines, if you generate a *.dxf file of the geometry in matlab and import it to eagle.

Can we import the .dfx file generated from Matlab to eagle and then use it to printing the PCB??

6. ## Re: Design of Spiral inductor(LItz wire) on PCB

Sure, dxf is often used to import PCB artwork, e.g. company logos. You can find ulp scripts for dxf import at the internet.

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7. ## Re: Design of Spiral inductor(LItz wire) on PCB

Originally Posted by FvM
Sure, dxf is often used to import PCB artwork, e.g. company logos. You can find ulp scripts for dxf import at the internet.

The layout of spiral coil(litz wire) has to be designed on two layer pcb(top and bottom) according to the matlab script and the same script has to be used in eagle for layout
generation.

Since the litz wire comprises of multiple strands based on the structure.
For example if we have 5 strands , out of it 3 strands are on top layer and 2 strands are in bottom for one sequence and for next its vice versa(2 strands on top and 3 strands in the bottom ) for other sequence. Only one strand changes its layer from top to bottom through a via.

The interchange of top to bottom layer is through a via , but in matlab script its just a circle.

Once importing the .dxf file to eagle do i have to replace circle by via ??

(i have attached an image file of spiral coil from matlab with "RED" indicating top layer and "Blue" indicating bottom layer)

8. ## Re: Design of Spiral inductor(LItz wire) on PCB

Ah...
I was thinking more of the 'shop security' coils you find sandwiched in plastic and stuck to goods...

Such a whatsit's cousin could be mounted like a heat-sink.

( Yes, yes, I know there's usually an expendable, reactive and/or non-linear element in the security whatsit, too, but only the foil 'trilobite' swirl is obvious...)

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