Hi,
I’m considering to purchase some PCBs through BatchPCB.com for some RF circuits. (making vias by hand vias isn’t fun, and RF boards requires a lot of them) By the information on Gold Phoenix PCB’s site it seems that I’ll get an FR4 substrate, but I couldn’t find any information about the substrates dielectric constant or thickness.
The web indicates the constant to be around 4.2 and 4.7, and allthough this makes little difference in microstrip width, I’d like a more accurate number.
Could you provide me with this?
And, have the idea of providing PTFE/Teflon boards been considered? (Theese are better for high frequency circuits)
Nitromarsjipan:
The web indicates the constant to be around 4.2 and 4.7, and allthough this makes little difference in microstrip width, I’d like a more accurate number.
Could you provide me with this?
And, have the idea of providing PTFE/Teflon boards been considered? (Theese are better for high frequency circuits)
Greetings (No Name Supplied),
I’ve been down this path with other vendors. The Er of the PCB material is hard to control, due to various vendors (for glass mats, epoxy) and variations in ‘stack up’ on multilayer PCBs. I’d say you have a 10% window on Zo of the finished PCB.
If the design is critical you have two choices: Ask the vendor to sort the material first or do a QC incoming inspection (with a Network analyser on a test coupon made on the PCB).
Either way you are well outside the BatchPCB concept.
If this is a show stopper for your project then it might be better to make a relationship with a local PCB house, where you can email, phone, or visit them.
Exotic substrates are available, and due to cell phones and wireless data appliances I would think many PCB shops have experience with them (and inventory of raw materials).
Sorry to be the wet blanket…
Comments Welcome!
Thanks for the reply!
I see, perhaps i should lower my expectations a bit.
I can get blank PFTE boards from a local vendor, with specified Er, but as i said I’m not very keen on making vias in it.
An option could be to contact a company called elprint, it looks like they can provide Teflon PCBs. However, last time i tried that their boards were very expensive, so it seems I’m better of making it myself. (I only need two or three boards, so it should be feasible)
Still, I’m looking forward using BatchPCB for all the non-rf boards of my project.
I was think of using a power plane and ground plane under large semiconductors as a decoupling capacitor.
I think it might be unrealistic after visting the link below to calculate the capacitance of a 1 inch square power, ground plane
http://www.daycounter.com/Calculators/P … ator.phtml
any ideas there is a lot of site with information but has anybody got some proven techniques