Solder ball crack

First some definitions, the two main types for solder masking near BGA pads are: 1 Pad, Non-Solder Mask Defined. In circuit board design, pads with spacing that does not allow solder (usually bumps) on the pads to contact the adjacent solder mask. [After reflow, this ends-up being a potato shaped ball, when looking at a section.] 2 Pad, Solder Mask Defined. In circuit board design, pads with spacing that allows solder (usually bumps) on the pads to contact the adjacent solder mask. [After reflow, this ends-up being kind of a mushroom shaped ball, when looking at a section.]

We like to use the solder mask definition on the board as is used by the BGA fabricator. As you imply, that doesn�t always workout well, when you have two suppliers. So, when we have to choose between the two, we choose non-solder mask defined.

When you say * �found the solder ball is out of shape after reflow�; we assume that you mean something other than the fairly standard ball collapse. Correct? Please tell us more. *�cross section view found that the solder mask opening is not good�; what do you mean? Solder mask defined?

reply »