Solder Mask Expantion!

[renatoferreira]

Here is a good explanation about this: https://www.autodesk.com/products/ea...-bridging-pcb/

[robertferanec]

Mostly we use 0.1mm / 4mil, but in same cases I go down to 1mil (if pads are very close to each other and I need to keep the mask between them).

[JohnsonMiller]

Hi Guys,

How much solder mask expansion is needed?
In reality thing did not go as was planned, sometime with a little difference. In PCB manufacturing this little difference result in shift between layers, especially and visible is solder mask. In this situation recommended zero mask expansion will cause problem as shifted mask will cover the pad partly. On the other hand too much expansion will expose nearby nets and polygons. What is your experience and recommendation?

BR,