Board Plating and Hole Plating
What exactly are the board plating and hole plating? The hole plating also named as PLTH, is shorted for plated through hole, which is plated with copper, just like the board plating. As for the board plating, it is formed by placing the boards in an electrically charged bath within 1 oz copper, then the whole copper surface is plated and copper can be drawn into thru-holes around the copper. Indeed, there are some relationships between board plating and hole plating.
The plating and hole-plating note
When designing a PCB, the plating or hole-plating note can be omitted if the plating thickness is recorded in detail in the material stack-up table. Besides, due to the difference of plating thickness is inevitable in different manufacturers, the plating thickness should be specified for keep consistency from manufacturer to manufacturer. However, you probably can skip to specify the plating tolerance, as the finished hole tolerance controls the plating thickness.
The plating and hole-plating thickness
Additionally, the thickness of board plating and hole plating is related to each other. As a matter of fact, the hole thickness is decided by external copper plating thickness. Generally speaking, the hole thickness is actually a little less (roughly .0004’’-.0005’’) than the external plating. This is fairly vital for determining the current carrying capacity of a plated thru-hole.
Importantly, if the plating is particularly described in material stack-up, all plated through hole should be plated less than .0004’’ (.0004’’refers to the external plating thickness shown in the table of material stack-up). On the contrary, if plating is not specified, all plated through holes should be plated less than .0010’’ [.025] of copper.
