Jack,
The chamfered bend if designed correctly is designed to provide a 50
ohm impedance around the bend (Touchstone can calculate it and also
has the formula included in the documentation). The general rule of
thumb for curved traces is that you want the curve radius to be 3 to 4
times the width of your trace. You can see why the "compensated
bends" are preferrable.
I'll bet 50:1 that the tin coat spec is outdated (or was a misnomer)
and that your company has been receiving solder coated (Sn63/Pb37)
boards. Tin can be plated up on the board by many PCB suppliers but I
don't know why you would want to do it.
In return, I hope you can tell me if you know of anyone with
experience using no-clean flux with RF board assemblies and whether
there are any problems doing this. I have heard of the flux becoming
conductive at high frequencies.
Frank Hinojos
Product Engineering Mgr.
Watkins-Johnson Co.
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]> *
* with <subject: subscribe/unsubscribe> and no text in the body. *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] *
***************************************************************************