Strapping fans to a prototype power supply PCB? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 07, 2022, 11:01:35 pm
content: Going to have quite a few (seven) of these cheap 0.4W fans spread around our prototype 2kW offline PFC/LLC converter PCB...12V fan 0.4whttps://www.tme.eu/Document/155940d94fffd4dbb8a29e964554b703/Product%2021.pdfWill “strap” them to the PCB with 0.4mm enamelled copper wire. This will be threaded through the lower two holes in the fan, and thru corresponding NPTH holes in the PCB that line up with these (so 4 NPTH holes in the PCB per fan)…..tie/twist the wire at the bottom of the PCB…then add tough nylon string to add to this….do you think this will offer enough support to stop the fans from blowing over?"Fan footprint", showing 4 holes, as attached

author: eugene
author_rank: Frequent Contributor
timestamp: June 08, 2022, 01:15:17 pm
content: Why copper wire? It's soft with low tensile strength. It's easy to stretch and break 0.4mm copper between two hands.How about steel baling wire?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 08, 2022, 03:40:18 pm
content: Traditional is holes big enough to fit a tie wrap... Why wasn't that the first option?For a more traditional mechanical solution, there's always Keystone (and others) right angle brackets.Tim

author: Faringdon
author_rank: Super Contributor
timestamp: June 08, 2022, 05:18:16 pm
content: Thanks very much, Tie wraps sounds great, we call them "Cable Ties" but its the same difference........Cable Ties/Tie wraps actually sound great, as they are malleable, easy to thread, and they pull really tight........i feel certain that this will definetely hold the fan upright?. The holes are 3mm, so i will make them a bit bigger so a really strong tie wrap can go through. Fan body holes are only 4.3mm so that will be max.I may back it up with some string....some of that really tough string from the hardware store.

author: mariush
author_rank: Super Contributor
timestamp: June 08, 2022, 06:27:02 pm
content: My question would be why those fans? They are noisy and produce very little airflow (CFM) and the static pressure is super low... if you want the air to move over heatsinks on the PCB you'd also need to make some air guide from cardboard or plastic.Maybe consider some blower fans which can do way more static pressure so the air can be pushed over those heatsinksFor example :https://www.tme.eu/en/details/mf50151vx-a99/dc12v-fans/sunon/mf50151vx-b00u-a99/Will use more surface but you could lift it above the pcb surface on hex standoffs - and you can use two pcb holes to screw the standoffs or directly the cooler to the pcb (but I'd probably use some rubber things to reduce vibrations)For example you could have one of these blower fans above the two heatsinks on the left side in your picture and you could have a cardboard guide or something to make the air flow over those heatsinks.Also ... how TALL is the box your pcb is gonna be in... looks like it's gonna be AT LEAST 40mm tall due to these fans you chose. If the box is closed, sounds like maybe you could have standard 92...120 mm fans but maybe 15mm thick instead of 25mm, and mount them on one side of the box and push air inside the box, and have ventilation holes on the other end of the box and the air pushed in by the fans would naturally go over the heatsinks and come out through those vents on the other side of the box..Think computer power supplies and how they use fans to push air into the psu and out the vent holes.ex 80x80 x 20mm tall :https://www.tme.eu/en/details/me80201v1-a99/dc12v-fans/sunon/me80201v1-000u-a99/orhttps://www.tme.eu/en/details/me80201v3-a99/dc12v-fans/sunon/me80201v3-000u-a99/Also for a 2kw prototype maybe you guys could have picked heatsinks more suited for forced air cooling (ex extruded, with more vertical or horizontal fins instead of those with 'spikes' around the part.The layout of the pcb looks bad, but too little in the picture to tell for sure... would love to see more of it.