board design

johnlong

Senior Member
Hi All
If having boards manufactored and populated
when designing a SMD 2 sided board is it acceptable to place vias in the components pads
to say GND and signals on top V+ on bottom power through the via in the V+ pad
regards john
 

oracacle

Senior Member
Not normally, but consult the company that is producing the boards, they will be able to advice what they can and can't do
 

rq3

Senior Member
Thanks oracacle
will do
As oracacle said, it's not normally considered "good practice", but it is commonly done, especially on cheaper consumer grade boards. The problem is that the via tends to wick solder away during the reflow process, potentially starving the solder joint.

If you decide to do this, use the very smallest via size that your board shop will allow, which will help prevent "solder stealing".

Note that there are a lot of surface mount packages these days that are heat sunk through a large ground pad under the chip, that REQUIRE ground vias to a large ground plane on the bottom surface of the board. The chip designer usually provides a "recommended" layout in these cases.

Most board houses these days have no problem with "micro-vias" as small as 0.006 inches in diameter, but check your shop for their design rules.
 
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