SMD and NSMD pad type for BGA package

What is SMD and NSMD?

There are two types of land pad patterns: Solder Mask Defined (SMD) pad and Non-Solder Mask Defined (NSMD) pad. The land pad pattern type differs depending on the solder mask opening.

Difference between SMD and NSMD pad types

Table 1: Difference between SMD and NSMD pad types

Solder mask defined (SMD) pad type	Non-solder mask defined (NSMD) pad type
In SMD pad type, the solder mask opening is smaller than the metal ball land pad.	In NSMD pad type, the solder mask opening is bigger than the metal ball land pad.
Select the SMD pad type to minimize underfill issues during the surface mount assembly process.	Select the NSMD pad type when board-level mechanical performance is important.
The solder mask prevents solder to spill over the SMD pad’s edge.	There is a gap between solder pad and solder mask in which the solder flows and strengthens the bond.

Consider the following table to select a PCB land pad pattern type when designing hardware with BGA package FAB024. See Figure1.

Figure 1: Difference between SMS and NSMD package

Figure 1

Source: KBA233770

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