Problem: When hand soldering a through hole connection for a pin connected to a ground plane, the time & temperature requisite to get good solder flow and good connection are considerably greater than that required for a pin connected to something other than a ground plane. This is caused by the thermals in the board design dissipating the heat from the soldering iron into the ground plane so fast that it's hard to get the pin & plated through hole up to temperature. At times this leads to failure even when it looks like the connection is good.
When I measure the thermals in Eagle Cad I see 20 mils four times each side of a 2 layer 2 oz. copper board. That's cumulatively 160 mils of 2 oz. copper dissipating the heat. The current on this pin is just a few mA. There is certainly no need for this much trace.
My idea is to modify the package in Eagle Cad to place an arc around the pin, some distance away from the plated through hole. I clone the arc so I have one on the top layer and one on the bottom layer. The arc, a copper trace connected to nothing, obeys the rules of spacing set in the design rules. I limit the arc to slightly more than 180 degrees to prevent 3 of the thermals from being generated on each layer.
This provides me with one 20 mil thermal on the top ground plane and one 20 mil thermal on the bottom ground plane, cumulatively 40 mils, still much more than I need for just a few mA passing through this connection.
As to pros & cons:
Pros:
This should help significantly with the problem of failed connections due to insufficient heat when soldering resulting in faster production and diminished failure rate.
Cons:
I can't think of any.
Can anyone else think of any reason I shouldn't spend the money to have some boards made up with this design and give it a try?
Has anyone ever tried this before?
Thanks!
When I measure the thermals in Eagle Cad I see 20 mils four times each side of a 2 layer 2 oz. copper board. That's cumulatively 160 mils of 2 oz. copper dissipating the heat. The current on this pin is just a few mA. There is certainly no need for this much trace.
My idea is to modify the package in Eagle Cad to place an arc around the pin, some distance away from the plated through hole. I clone the arc so I have one on the top layer and one on the bottom layer. The arc, a copper trace connected to nothing, obeys the rules of spacing set in the design rules. I limit the arc to slightly more than 180 degrees to prevent 3 of the thermals from being generated on each layer.
This provides me with one 20 mil thermal on the top ground plane and one 20 mil thermal on the bottom ground plane, cumulatively 40 mils, still much more than I need for just a few mA passing through this connection.
As to pros & cons:
Pros:
This should help significantly with the problem of failed connections due to insufficient heat when soldering resulting in faster production and diminished failure rate.
Cons:
I can't think of any.
Can anyone else think of any reason I shouldn't spend the money to have some boards made up with this design and give it a try?
Has anyone ever tried this before?
Thanks!