first pcb steps - sallen key filter

[keith1200rs]

Probably, but at a high cost. You have used 4 thou tracks and a couple of 0.15mm holes. These considerably add to the cost and are unnecessary - you should change them. Also, you have use 0402 components which, as FvM pointed out, may not be available in dielectrics suitable for a filter. I normally use 0603 components and often end up having to use 0805 in filters, sometimes 1206, so I can get the values I need in the dielectrics I want.

You should use the DRC rules applicable to the company you intend to use to make the PCB.

Keith

 

[denver56]

Probably, but at a high cost. You have used 4 thou tracks and a couple of 0.15mm holes. These considerably add to the cost and are unnecessary - you should change them.
Keith

Which size of tracks and holes should I use in your opinion ?

 

[keith1200rs]

I would normally use 0.2mm minimum track but 0.15mm if really necessary. For the gap, I would try to use 0.2mm minimum but 0.15mm if really stuck. For holes, 0.3mm minimum finished hole size minimum, 0.2mm annular ring. Normally I would try to use larger hole sizes. With rules something like that you should be able to get most reasonable suppliers to make it without a problem.

Keith.

 

[denver56]

so basically the rule is "bigger is cheaper", right ?

 

[etmabreu]

so basically the rule is "bigger is cheaper", right ?

Yes. Usually, if less care is needed in production, often yield is higher and price is lower.

 

[keith1200rs]

so basically the rule is "bigger is cheaper", right ?

Up to a certain point. Once you get to those sort of design rules then almost anyone can make the boards and you can get competitive quotes. If you want 0.1mm tracks and 0.15mm vias then you will have a lot fewer companies to chose from and the price will rise accordingly. Also, with very fine rules it becomes more appropriate to consider electrical testing of the bare board.

Keith.

 

[dewasiuk]

Re: first pcb stebs - sallen key filter

You should calculate the PCB track impedance to match it to source impedance.

That would be for high frequency applications or when you want max power transfer. Most low frequency designs need impedance bridging rather than impedance matching, which I'm guessing that's what the OP wants because he didn't specify what frequencies he/she is working with and Sallen-Key topologies are more commonly found in low frequency designs.

 

[denver56]

Re: first pcb stebs - sallen key filter

Hi people! I'am going on with the work. Cause the high number of components I had to increase board dimension. I increased it in "board mode" but when I add components in the new portions of board Eagle warn me that it's impossibile to put outside the allowed area: so it's seems that it doesn't recognize the new extended area. Do you know why ? Thank you all!!

 

[keith1200rs]

Are you sure it is not a PCB size limitation of the version you are using?

Keith