Hi All, I have a query regarding a PCB production discrepancy appreciate if someone can help.
In the attached image I have given extracts out of EP2W+ RF splitter Schematic, Gerber and photo of the pad from a previous PCB and finally the one I just had done.
Even though the Gerber shows individual pads as separated in the latest manufactured PCB all the pads not used are merged together. I’m trying to figure out what probably have cause this and whether this is acceptable?
Cheers
Ryan
Plenty of pins are connected to ground in the Gerber already afai-can-see.
The production version just couldn’t manage the solder mask minimum width that you needed, to get single pads.
Underneath it’s all ground anyway - as per your Gerber.
Or in other words - your fab house isn’t capable of the finesse you want.
If the gerbers you send to the Fab have individual pads, then it looks to be a production issue.
The Silkscreen marks also look unusual, which suggests that it is not a footprint from KiCad’s default libraries.
One thing you can check is to measure the clearance between the pads in the gerbview, and compare that with the production parameters of your Fab.
But it does not look as it’s below the resolution the fab can make. Pins 4, 15 and 26 do have the clearance, and the (presumably) QFN above it has the same pitch.
I assume all those pads are for GND and therefore not a real error. Do you have a solder stencil to go with this, and how does that look like? Such a big cutout in the solder stencil deposits a lot of solder on those pads, and may also weaken the stencil itself.
@Joan_Sparky thanks for the reply.
I had couple of production issues with this board it appears that minimum clearance is 0.25mm for 1oz/black solder mask and this IC has 0.2mm clearance. This is something guys doing pre-production checks should have picked up and followed up with me.
@paulvdh thanks for the reply.
It turned out minimum clearance for fab is 0.25mm and this IC is 0.2mm, I don’t have the stencil to check unfortunately. Yes the all the other pads are GND except for 4, 15 and 26. I didn’t think it would be a problem but wanted to confirm as I am still learning…
This same board had another similar issue with a battery charger IC mainly with 2 pins but others pins are not great either…
This seems to be an unusually coarse clearance. Clearance in the order of 0.1mm are more common these days.
It seems that your board manufacturer can not meet the accuracy of your PCB, and during larger production runs this may lead to random etch faults on other locations of the board, even if these long combined pads in itself are probably not a big issue. Such faults can be under the soldermask, and very difficult to spot.
Some PCB manufacturers can do an “electrical check”, but I’m not sure if this only checks for open connections, or only for shorts.
I got that idea too, but the resolution of your screenshots is too low to base any conclusions on.
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