Macbook A2159 820-01598 ISL Pads

[jimanez11]

Have a macbook A2159 - board number 820-01598 that needed to have U7000 replaced. When I lifted the old chip, I lost two pads. I think I may have been lucky with which pads I lost, but wanted to make sure before soldering on the new ISL. Pads lost were 27 and 28 (on boardview) / F2 and F3 on schematic and are listed as:
- F2: NC_CHGR_EN_VR1
- F3: NC_TP_CHGR_AUX_OK

Because these are noted as "No Connect", is there any point in me trying to salvage the pads or can I leave them alone and attach the new ISL as is?

Any suggestions or guidance is appreciated.

[mon2]

Re: Macbook A2159 820-01598 ISL Pads

Searching for the missing pad net names came up empty. They are indeed no connects (NC). You should be ok to leave them floating.

The part is a tiny bugger (WLCSP package) so approach with patience.

[jimanez11]

Re: Macbook A2159 820-01598 ISL Pads

Awesome - thanks for the reply. Would there be any harm / benefit to grounding them? That way I wouldn't have to worry about the solder balls running away or potentially bridging with nearby balls when flowing the new ISL?

[jimanez11]

Re: Macbook A2159 820-01598 ISL Pads

Never mind about connecting them to ground. Some basic research resulted in a resounding no. Will go ahead and float them. Thanks again!

[mon2]

Re: Macbook A2159 820-01598 ISL Pads

Just leave them as no connects. I think the balls will melt and become like a soft pillow with no mating pad but then should solidify when cool. Don't think they will float around due to the isl9240 having a pad for each on its belly. Do not short to other logic or ground as we do not know how these pins will react.