SMD: "Solder-Mask-Defined"

NSMD: "Non-Solder-Mask-Defined

I am making a thin flex-PCB (0.2-0.3 mm) on which I am going to mount a component which has SMD pads.

I would like to also make the pads on the PCB as SMD rather than NSMD, but I am worried about the production tolerances as well as mounting tolerances of the coverlay usually used on flex-pcbs instead of a liquid solder-mask.

So I am here hoping that someone with more experience working with flex-PCBs and coverlay can tell me whether I can make these pads as SMD using coverlay, or how else I should go about making SMD pads on flex-PCB, or perhaps tell me that it is not possible or inadvisable.

Below are screenshots of the spacing between the pads, the purple pads are the openings in the solder-mask/coverlay and the red pads are the underlying copper pads.

I have done this before on rigid PCBs and I would be comfortable with these dimensions/tolerances if it was not a flex-PCB with coverlay.

vertical distance between soldermask/coverlay openings vertical distance between copper pads horizontal distance between soldermask/coverlay openings horizontal distance between copper pads


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