gusmanb
Requirement for soldermask/coating over the buffer chips?
Hi, in many pics there some sort of soldermask or glue over all the pins/package of the logic shifters. How important is it, and would normal uv-cure soldermask repair stuff be the correct thing to slather over them? Or does it need to be special stuff to avoid any capacitive effects? Recently just swapped the pico2 for a pico2w to try the beta 6.5, and it's GREAT! I would like to cover everything in soldermask because I have very bad luck and will probably drop 50 resistor legs across the board randomly, heh.
You mean the glue in this image? I'm quite certain that's just plain standard UV-glue/resin to hold the bodge-wires in place. Real UV-solder mask resin sounds much more expensive than the regular types.
The idea to use that as a "conformal-coating" is intriguing, I've only used it for tacking stuff together or holding bodge wires, but it would probably work reasonable well for making insulation barriers. I have to try that and see how it works - thanks.
I'd worry more about setting the pcb down onto something and have the bottom-side solder joints of the pinheader short out rather than having something drop on top of the pcb though. ;-)
I had seen a few different pictures, with stuff on all 4 sides. Not sure if it was a custom thing PCBWay did, or some 3rd party mfg/cloner, of the LA6 with resin. And yeah I'm talking about the normal AliE UV cure soldermask stuff that is $3 a tube in a rainbow of colors. I wanted to cover the buffer chips, and solder pads of the pico. When I swapped the pico2w on, the SWD port is in a different place (center of board), than the normal pico/pico2 which is at the end of the board. I was GOING to put some kapton on the bottom of the pico2w before soldering it on (directly on the board, no pinheaders), but got sidetracked and forgot. I just prefer to spend a little bit of time on prevention, especially with my luck!
I just wasn't sure if putting the normal generic UV cure soldermask/resin from AliExpress might affect things in ways I couldn't understand, especially at higher frequencies, the pins on the buffers being bridged by dielectric resin might have capacitive effects? The TSSOP14 has 0.2mm gaps between the pins
I think the UV coating was just to hold down the bodge wires with the early version of the version 2 PCBoard. I ordered a batch of boards from PCBway early August 2025. The boards PCBway gerber files have been updated and you won't need any bodge wires.
The 0402 resistors and capacitors were a challenge. ( 0603 is my hand solder limit ) I cut myself a stencil on a laser cutter and used a reflow heat oven for the level converter chips, resistors and caps. I had a second stencil to lay down even solder paste for the Pi Pico and used reflow hot air for the Pico. ( My oven toasted the top of the Pi Pico boot button when I tried to do a board all at once.)
.. next time I'll order stencils with any boards. The Kicad files are available to make a modification to take larger size 0603 passive components.
