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Routing 0.4mm pitch LGA?

angelsix , 10-20-2015, 01:05 PM
I can't find a way to route an BGA25 package at all.

Even micro vias (0.27mm) and 4 mil tracks cant get out. Any suggestions on what to do without making the PCB super expensive?

robertferanec , 10-21-2015, 12:42 AM
Couple of options:
- use the same chip but in different package
- use more expensive PCB - smaller tracks or VIA in pad
- talk to your PCB manufacturer. Some of them may be able to use cheap technology and make a few exceptions - to use couple of tracks thinner as they normally use for that technology, but it only can be in one small PCB area.

It looks like, the package you use is designed the way you can connect the pads together - only the C4 VIN seems to be in a weird position. Is not possible to connect C4 to one of the pads what are close to it?

Also, in some cases you can find a demo board (where the chip is used) and you can check how they did that.
angelsix , 10-21-2015, 01:48 AM
Its a MODE switch for a power regulator and thats the only issue it needs to go high. The pin above it is Enable which would usually be high so it would of been no problem, however I have a switch for enable so I cant do that.

I've swapped to another chip as they had no other packages. Meant a total redesign of schematic and layout for power section but was good practise and will make me look more carefully at 0.4mm pitch chips again in future
robertferanec , 10-21-2015, 02:00 AM
The right approach!
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