Hi All,

I recently had our production manager come back to me and ask that I alter a 4 layer PCB design to the 'cheap way' in the attachment, versus the 'expensive way' I used.

Can anyone comment on this? Are there any repercussions of me allowing him to alter the process?

Regards

 

How high frequencies is this board? The only pitfall I see is dielectric constants of the board, and that would only affect really high frequencies. I have to say I'm no expert in this though, just my 2¢.

Oh, then there is voltage breakdown, which is less common as an issue.

 

How high frequencies is this board? The only pitfall I see is dielectric constants of the board, and that would only affect really high frequencies. I have to say I'm no expert in this though, just my 2¢.

Oh, then there is voltage breakdown, which is less common as an issue.

I did find an e-book which discussed this briefly. Although prepreg is the same material, I guess the tracks are more prone to 'sink in' a bit during fabrication and as such the thickness can be slightly less than intended.

This would impact the dielectric and clearances slightly, but as far as I can tell this cannot be predicted to such a degree and must be assumed to be the same as the core.

I don't see any reason why this assumption is not valid, considering the material is the same, only the process of application differes.

 

I have always used the standard method of board production. We made processor boards with clocks of 30 and 40 MHz. Our analog sectioins routinely went up to about 1 MHz.

Even the other division of the company, working on RF circuits, used the standard method of board production.

Unless you have a specific reason, that is somewhat measurable and reproducible, I would always start with the standard method. The standard method is pretty flexible with layer thicknesses and such.

There's 2 more cents.

 

Sounds good to me. Thanks.