So I am about to order a 2-layer board from JLCPCB. My board has, on one side black solder mask with white silkscreen text and through-hole switches. On the back, there are smd’s.
The front with the tht switches is also the product front plate, so I would like to have the holes as nice looking as possible.
So my question is, do I need to have the mask (the mask pads that excludes the black solder mask) on the front side where the holes will be drilled or can I just have them on the back layer where the pads are, or will that leave a bad surface finish when JLC drill the holes.
IIRC from watching the production steps of a fab I used, the drilling is done early in the sequence, before mask is applied. But I don’t know what sort of bad finish you fear might happen.
I guess I was thinking that if the mask is applied first, then the drilling could tear the edges of the solder mask or something like that. I am probably just overthinking it, but all the holes, npth or not, have a mask layer on both sides to keep the solder mask from being applied, and I am not 100% sure why that is.
Applying the solder mask at hole ends with solder mask in the hole. You can see it at vias. So it would be not good to apply the solder mask on NPTHs, I think.
There’s a difference. Via holes are plated through-holes. NPTH are mechanical holes. Manufacturers make plated holes very early in the process, obviously before applying solder mask in any case. But NPTH can be made very late, possibly even using the same tool in the same step as cutting out the board edge.
If I recall correctly, JLC specifies that NPTH holes should be marked on the mechanical layer (Edge.Cuts) else they will still be plated on the inside despite not having any copper pads. I believe they are drilling NPTH mounting holes at the very end, with all the slots separating each board.
You misremembered. NPTH are specified in the Excellon NPTH file. Slots are in the mechanical layer though.
Anyway I think OP is overthinking this. I leave the soldermask layer on the front by default and I have never noticed any bad finish (tears? burrs?) due to drilling.
Agreed. No problem with edge cuts or mechanical holds on solder masked areas both with JLCPCB and Aisler. (These are the only manufacturers, I have experience with)
I will probably keep it as is, but ask jlc to send me the production files to verify that everything looks ok. I will post an update when the boards arrive.
Thanks again
