I just had a brainfart. I have a need for an arduino board with castellated holes. (my own design also carries a max485 IC) I have a PCB design ready to order with smd assembly but it would mean a bulk order which sets me back like atleast €450,- I am not yet ready to start with the mass production. As an intermediate solution I want to try out an arduino pro-mini. I like that it is flat on the bottom side, it is 12mm shorter than a nano every and there is a 3V3 variant (which I need) My brainfart: can you sand off the edges to make it's holes castelled holes? without breaking something that is :smiley: I do not have one lying around at this moment to test. Looking at the photos there seem not to be traces between the outer holes and the edges. At work we have a big sanding machines which should make the job easy, Kind regards, Bas

The Arduino Micro board layout picture shows no traces outside the holes so sanding off the edges should not cut any traces.

I'm curious to see if this is possible without actually damaging the very thin layer on the holes themselves keep us posted if you try (and wear a mask/goggles)

Though I program things in dis company here, I always got me a pair of safety goggles lying on me desk :wink:

My Pro Minis have A4 and A5 (I2C) on the interior of the board, not along the DIP edge. Does that work for you?

Can you design plated through holes on the board edge, then have your board house machine V-grooves through the center of the holes? Then you can break off the tab and have what you want. For production, make many boards in a panel so the V-grooves are between adjacent boards. Break by hand or use a segregator to cut the v-groove.

See these posts. [image] Share tips you have come across General Electronics If you purchase a board like a Buck Converter 'and' the board doesn't have components on one side, you can use it as a Castellated daughter card on a PCB you design. Use a table sander to take off the edge(s) of the PCB where the through solder holes are located. For insulation/isolation purposes, place Kapton tape on the flat underside of this PCB. When 1/2 of the buck converter hole is removed, solder the remaining plated through hole to the motherboard's pads. On a none castellated edge, … [image] [image] Share tips you have come across General Electronics Hand Soldering Castellated Components It can be difficult to solder castellated components as the area to the left and right of the cove is, usually, glass epoxy. If you follow the images below, you should achieve good results when hand soldering these devices. [0] [A] [B] [C] [C1] [D] [E] [F] [G] [H] [I] [J] [image]

I am aware. I will make a keepout zone. Were I to lack 1 or 2 whole IO pins, I will happily solder a wire to A4 and A5. I also miss A6 and A7. I often use A7 in combination with a resistor divider in order to set a peripheral address. @Larry I have lots of buck converter backpacks in many designs. I still cannot beat the prices to add my own buck converter design for the small amounts. And for those four solder pads, the labour is not that much. I happen to find a stray pro-mini in my programmables inventory. I hid it in my pocket so I will magically find it tomorrow @ work. That always works the other way around when I suddenly find a CF card in my pocket. Tnx for the advices. I'll let you know if I break any of the tiny little holes... or not. Regards, Bas

[image] bask185: my own design also carries a max485 [image] bask185: an arduino pro-mini... there is a 3V3 variant (which I need) The MAX485 is AFAIK 5volt-logic only. Maybe you need the MAX3485. Leo..

[afbeelding] Had to cut away an led and resistor. They didnt seem important :see_no_evil: I cannot recommend this machine. It is hard to it straight without an extra tool. I just did it by hand and eye vision (and yes I wore me goggles) [afbeelding] [afbeelding] [afbeelding] [afbeelding] I almost lost pins 6 and 10 :see_no_evil: Sanding does work though The copper is now exposed. If I solder all the pads (and the remains of pads 6 & 10) completely so that no copper is exposed will it eventually still oxidate and 'go bad' or can I expect alteast 10 years of loyal service? Another question. The bottom side shows me 'the simple', '5v' and 3 different clock frequencies. Judging on the 5V I think this is a 5V variant. Those clock frequencies (8, 16 and 20MHz). Can I select any of them in the IDE? The tasks only exists out of reading some switches and control some LED. I do want to use SW serial libary for B2B communication. I'd prefer 8MHz in order to reduce current consumption. Nvm found the fuse settings in the IDE Kind regards, Bas

Hi, Make sure when you solder, that the solder runs the full depth of the opened plated through hole, to make sure you cover any cracks in the plated surface. A good resin cored lead based solder. Tom... :smiley: :+1: :coffee: :australia:

Can you sand a pro-mini to make it's holes castellated

Projects General Guidance

LarryD January 30, 2023, 6:30pm 11

See these posts.

Topic		Replies	Views
Share tips you have come across General Electronics	1429	384886	July 23, 2026
Will this work? Atmega1284p Schematic Hardware Development	230	2389	May 19, 2026
Confusion on basic hardware, involving FSR, boards, shields 3rd Party Boards	16	309	January 1, 2026
Mounting Nano/Pro-mini to pcb (as flat/low as possible) General Electronics	4	4476	June 16, 2019
Pro-Mini vs Mini Pro Mini	6	842	January 26, 2025

Can you sand a pro-mini to make it's holes castellated

Related topics