Electronic – cut off an NC pin from an IC


I am designing a circuit using an IC, LTC7004, which is a high-side MOSFET driver. There is one pin (10th) marked as NC.

NC (Pin 10): No Connect. This pin should be floated.

In my PCB design, I'm pulling out a track from the 8th pin which is the pin to connect the source of a FET as in the figure below.

Enter image description here

If I can pass the bootstrap (9th) track over the 10th pin, I can have a wider track for the source connector than the one I currently have.

Since the 10th pin is a no connect pin, will it make a mess if I bend and break away the 10th pin from the IC? (Then I can design a custom foot print to have only 9 pins with the MSOP10 package dimensions). Should NC pins need to be soldered onto a PCB with isolated pads by any means?

Best Answer

From an electrical point of view, NC pins need not to be soldered. Ripping it off or soldering it to a (small) pad makes no difference.

From a mechanical point of view, having it soldered or not can make a difference though. I am fairly sure that the manufacturer recommends a certain footprint in the datasheet, and that that footprint includes the pad for pin 10.

If you are confident that the other pins give enough mechanical stability, you can just cut it away as per your plans.

An even better option, from a manufacturing point of view, would be to just remove the pad for pin 10 from your PCB, and route the track from pin 9 right below it. The solder mask will guarantee electrical isolation, and there is no need to add a manual step to the manufacturing process. As Tom Carpenter as commented, there is a drawback: the solder mask thickness can prevent the chip to seat flush on the copper, thus leading to soldering issues in some cases.

Whether you trust your solder mask enough for this is a decision you should make.