Soldering advice for button shim, scroll phat hd, and using phat diffusor

  1. Is there any special advice on soldering a button shim and scroll phat hd onto the pins of a female GPIO extension header? Please note that I don’t solder them to the Pi’s header, but to a female extension header. I suspect that these shim and and phat need to be soldered separately, but not in one go, correct? Anything to watch for when soldering the shim, so that I can later easily solder the phat on top?

    Or would the stock female GPIO header with 3mm pins suffice?

  2. Any special suggestions on how to shorten the extension headers so that I can still mount the diffusor phat on top? The diffusor unfortunately covers the pin area, but that’s understandable.


If it was me, I think I’d solder the Button Shim on the header first, flush with the header. Then the scroll pHat leaving some space between the shim and the pHat. Line it up nice and level and tack one pin on one end of the scroll pHat with your soldering iron. At normal height, not protruding enough to bother the diffuser. Then get the scroll pHat nice and level and tack one pin at the other end with your soldering iron. If your satisfied with how it looks, then go solder all the pins. If not, unsolder one end and adjust it.


Found my Pimoroni order yesterday in my mailbox and did the soldering today. I soldered on the button shim onto the female 2x20 GPIO header with 11mm pins. Next, I placed the scroll pHAT HD on top, with only approx. 3mm space in between, and soldered it on. Then I trimmed down the overlong headers with a small wire cutter. This gives a compact package.

So, on to mounting the pHAT diffuser. Unfortunately, the black bolts that come with the diffusor won’t work (see the images below), and they give a rather wobbly result when I tried them before soldering the button shim and scroll pHAT, I resorted to double-sided sticky tape (tesa powerbond outdoor). To get proper spacing between the diffuser and the LEDs I used two layers of that really sticky tape, sticking it into the two places to the left and the right of the LEDs. Getting long M2.5 bolts really isn’t easy (and then in black too)…


Looks good. I’ll be ordering one of those diffusers at some point. I’ve been cutting the big ones to fit my projects with my dremel tool.


@thediveo: you should be able to snip the bolts with a pair of snips to make them shorter and then they’ll fit in that gap neatly.


Screw the nuts on over the bolts before you cut them. Then if the threads get messed up backing the nuts off will make them usable again. If you have a dremel tool with a cutting wheel I’d use that.


I soldered something along the same lines as you describe here. In my case a double height header onto a pico HAT Hacker and then an onoffshim on top. I first soldered the double height header onto the pico HAT Hacker board. Use the minimum amount of solder so that the shim fits close to the board (i.e. It is not held away by big solder blobs on the pins of the header).

Then solder the shim onto the header pins, again taking care to use a minimal amount of solder and not get it onto the header pins very far above the board (as that makes it harder to push on additional headers such as a second HAT).

I used my pico HAT Hacker to add a second colour coded GPIO header. So I can fit this onto any of my Pies, giving me an onoffShim, I can then add a HAT and still access the full GPIO header (or add a Blinkt alongside the HAT). See photo here:


The bolt length isn’t a problem here, because the mounting holes almost perfectly align. It’s thd hassle of having to fiddle two or three nuts per bolt, where one requires pliers to position and hold it, so it’s not turning with when tighting the bolts.


I go front to back when installing a diffuser. I put the screws through the diffuser, then put one or two nuts on each screw and tighten them down. Then my Hat or pHat goes over the screws and I attach my standoffs to the screws to hold it in place. (Or add the last set of nuts). Then I attach my Pi with screws (or a second set of standoffs) to the standoffs. Etc.
Screw > diffuser > nut > pHat> standoff > Pi