DO-214 is a standard that specifies a group of semiconductor packages for surface mounted diodes.

The standard includes multiple variants such as

DO-214AA (SMB), DO-214AB (SMC), and DO-214AC (SMA).

DO-214AC (SMA) is the smallest,

DO-214AB (SMC) is the largest.

DO-214AC (SMA) < DO-214AA (SMB) < DO-214AB (SMC)

 

 

从以上的图片看来，这三种封装看上去差不多，没什么区别，但从实物体积上来分，可以看出：

SMA < SMB < SMC