pcbpcb-designpcb-fabricationrouting
Once I mistakenly placed a via on 0603 pad and didn't have any problem on soldering. I am routing another board now and I could save some space by placing some vias (0.3mm) on a 0603 pad. I wonder if it is a used technique or is it a bad practice? Would it cause PCB or PCBA production, or performance problem?
The via connections are low frequency (max 1.2 kHz) and related connections looks like this.
I hope I don't contradict anything said on the previous question's answer!!!
The feedback point should be taken from as close to the output pin as possible. Note the track on the non-component side of the LTC3536 document.
I'd use a full ground plane on the underneath all round but the low voltage end of R7 needs to get to pin 2 and then pin2 needs to star point under the chip to local full ground plane.
I wouldn't tee off R27 (and pin 3) to feed the top copper that connects to the bottom copper (GND Plane) - I'd let (what you've called) GND plane flood thru to power ground where R11 is and as far up as nearly the analogue ground plane.
The track from pin 10 should attempt to keep to the top layer as much as possible so as not to interrupt ground planes underneath.
According to some PCB production service design notes, it can be an issue:
If the track leaves the pad at a very sharp angle, it may create a "peelable". This refers to narrow pieces of photo resist which can come away during processing and cause shorts. You could also state this as advice not to violate track/track and track/pad design rules even for copper within the same net.
Best Answer
The industry term for this is via in pad.
It's not a problem when you hand-solder components.
It can cause problems during automated SMT assembly. Solder, which was applied to the pad as a solder paste, can drain through the via and there will be an insufficient amount of solder to hold the part.
(Image came from this blog entry, which illustrates the issue.)
There are methods in which the via in the pad is filled with solder or epoxy. That is done prior to SMT assembly. That adds to cost of assembly, so the benefits from the via-in-pad need to justify that.
Related
older thread: Vias directly on SMD pads
article: Via-in-pad guidelines for PCBs