We always have in our designs situations where one pin of a row of SMD discretes (mostly 0201's) is tied to a solid plane of copper with no thermals. Over the years, our fab houses flag this and have requested to adjust the mask opening on the plane connection to make it smaller so that it doesn't become a larger 'pad' than the other side of the discrete. We've had this done this successfully over the years. The question has arisen whether we could make this adjustment ourselves within Allegro so that the fab house doesn't have to do it. I can't think of a quick and easy way to do this. How does everyone else accomplish this? Thanks for any insight you can offer.
Thank you all for your responses. In some cases, we can use thermals. In others, we cannot because too much of the plane would be diminished (some of these planes are powers, not GND). The option of alternate footprints with soldermask defined pads is probably the best. Thanks again.
Hi, you mentioned one side of a bank of 0201's are swamped in a copper plane. Now I'm just guessing here. But, I assuming the other side of the 0201's are connected by real small traces. Is that correct? if so, how in the world would a assembly supplier sign up to this? They would state that the copper balance attached to these parts will force them to tomb stone like crazy during re-flow! This is PCB 1:1 here! a real no no.
So, my suggestion would be to pull the parts back from the plane and connect them with a small short as possible thin trace matching the other side of the part to the plane. And as far as RF concerns if any. Well, you'll never know until you build and test your board. My guess you will be fine. But, get actual data I always say and prove it.
I'm in agreement not to allow suppliers to mess with your design. Even thou IPC states 1:1 mask.