In your message dated Thursday 31, October 1996 you wrote :
> Does anyone have experience and/or reliability data to support the
> requirements for the minimum conductor width due to hole breakout called out
> in IPC-RB-276 for class 2 product?  The requirement calls for 80% of the
> connection to be intact.  If we totally drill out an external land to trace
> connection (0% connected?) then "reconnect" it with the plated copper will
> it at all be reliable?  Thanks in advance for your thoughts.

Hello Gregg,

It will depend on the ductility of the plated copper. We must have produced 
thousands of pwb's with landless holes where the track leads straight into the 
hole, and have not seen any failures of the connection due to thermal cycling.

However, with the introduction of CAM it is easy to globally edit all such pads 
with a tear drop which broadens out the track to the full width of the pad. This 
does not cause any spacing violations and we do this as a matter of routine with 
the customer's consent. It is also good practice on inner layers to increase the 
contact area within the hole.

Paul Gould
EMail [log in to unmask]

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