SMD Pad and NSMD Pad

ScarletOhara

Generally there are two kinds of pad designs: copper defined pad(none soldermask deifned pad-NSMD Pad) and soldermask defined pad(SMD pad).
NSMD Pad:

The solder mask openings are larger than copper pads.
The advantages of NSMD pad are
-         Good Sloderability: Because there are Three Sides of PAD, the WHERE CAN BE Applied TiN.
-         It IS Possible to Precisely Control Also at The position and size of at The PAD.
-         It's Easier to Desing traces Because at The PAD IS Relatively Small size.
The disadvantage of NSMD pad are
-The         copper foil is easier to be torn due to the external forces.
-         Because Small IS The PAD, PAD The strength of The IS attached to The Relatively Small Circuit Board
SMD Pad:
Soldermask defined pad (SMD) is that the solder mask is coated on the some copper foil and the copper foil which is not masked forms the pad. The soldermask openings are smaller than copper pads. Solder mask defined pads are suitable for fine pitch components, often used with BGAs. The solder mask covers the pcb area between adjacent pads and overlaps on top on pad edges.
The advantage of SMD pad are
-         THESE PADS The Will Effectively Improve The strength of PADS.
-         Improves at The strength of BGA, and Reliability.
-         It's A Good Choice for Portal Electronic Products's.
The disadvantage of SMD pad are
-         Worse Solderability: Because at The Solder mask by Will BE affected by at The High temperature reflow in at The Oven, Which by Will Affect at The Area of TiN at The Solder Paste.
-         Worse position of at The PADS: Tolerance of Soldermask at The Bigger Within last at The Copper IS, SO IT May Affect at The size of at The PADS and at The relative position.
-         Because at The Copper Increases are, the trace Area at The IS Relatively reduced, and at The Design Becomes More 'apologetic' the trace.

-The         fabrication process is more difficult, and it requires high precision, greatly increasing the manufacturing cost.