Why are 1.5mm thick PCB not common?

[samuelr]

Hi

I had someone request for a 1.5mm PCB. This is the first that I have even heard of it, but after some searching found that most in Europe seem to be prototyping with 1.5mm thickeess. Its just 0.1mm from the common 1.6mm FR-4 type boards. I am not sure if its just that they ignore the 0.1mm or if there are really boards out there that are 1.5mm or if the boards really are 1.5mm but considering the solder mask + 2 x layer copper (2 x 0.035mm)
Its comes to 1.5mm? Anyone knows for sure?


Samuel

 

[KlausST]

Hi,

I´m really not sure, but i allways thought:
bare FR4 material: 1.5 mm
2 x 0.035mm copper = 0.07 mm
2 x ?? solder stop = ??

in total: about 1.6 mm.

But there will be manufacturing tolerance also.

Klaus

 

[Warpspeed]

Back in the days of imperial measurement, 1/16 inch was (and still is) a pretty universal standard sheet metal thickness, and the original standard for PCBs.

And 1.6mm has now become the new metric standard for many things, as its much closer to the old 1/16 inch than 1.5mm.

1.5mm = .0591"
1/16" = .0625"
1.6mm = .0630" its only half a thou different.

And that may be important where boards plug directly into card cage runners and edge connectors which were once very popular.