silkscreen over traces causes impedance discontinuities?

[Amal.v.s]

hi guys,

how silkscreen over traces on pcb will cause impedance discontinuities...?

thanks.

 

[smijesh]

No Silk screen materials are high dielectric materials, it would not have any effect on circuit impedance, may be influence in high frequency(MHz)

 

[marce]

Because it is causing the signal to see a change in the dielectrics it passes through as it travels from a to b, most of the time solder resist/air, when it passes through some silkscreen ink you have solder resist/silk screen ink/air.

 

[volker@muehlhaus]

how silkscreen over traces on pcb will cause impedance discontinuities...?

What length, what frequency?

 

[dick_freebird]

I imagine the question is, "how much". A professor will insist
there will be "some". Someone doing the testing may say
"so what, it's in the noise". Numbers matter.

 

[CataM]

What length, what frequency?

Say length=L and frequency=f. Isn't there a formula ?

 

[c_mitra]

Silk screens are usually placed over the solder resist and that gives some space. If the wavelength becomes comparable to this scale (less than 1mm) then there may be some observable effects. By the way, 30GHz approx corresponds to 1 cm wavelength....