Reverse Mounted LEDs (Diffusing LEDs through the PCB material)

In this video we will look at the process of reverse mounting LEDs so they shine through your PCB which gives a really nice diffused effect!
I recently posted an image on twitter of a tester board I designed for trying out different mounting positions for side mounted LEDs and the tweet generated some interest so I thought it might be worth making a video about it.
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Links:
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Side mounted LED tester (including links to side mounted LEDs I used) : github.com/witnessmenow/Brian...
Dave Darko's word clock: hackaday.io/project/19388-pcb...
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[@andymouse]

Different markings for different colours is madness, I bet the air turned blue when you sussed it !...cheers.

[@upperairs]

I know for me it has been tough to stay motivated and complete projects. I'm always thinking about the next project.

[@CarlBugeja]

Intreseting analysis!!

[@MiggyManMike]

FR4 as a defuser material, now that might be a useful idea :)

[@PsiQ]

Uuuuuh! He 's alive ! :-) edit: i guess it would be cheaper to get the flimsiest and cheapest (but transparent) pcb without any components AND a normal assembled smd pcb with the leds and screw or glue the cheapo one ontop. Or maybe get the standard pcb coated with a diffusing conformal coating.. i guess if you wanted to do that afterwards and maybe even get it off again you could use plastidip spray.

[@TheEmbeddedHobbyist]

if at first you don't succeed FTFD ;-) this is one of reasons that when we produced a company footprint for a every component we used, the QC department had to sign it off before we could use it for production. They checked it to the datasheet and company design rules, so you lost a lot of brownie points if you missed anything. Easy to lose, but a bugger to get them back and pointed out too you at evey design/production meeting. Electronic design happy days!, but now well behind me. :-) bugger me forgot to add, also try tin foil between a layer of hot snot to refelect light back, used a lot in backlit aircraft panels to bounce light about to get even brightness . The tin foil not the hot snot.

[@MrChildren87]

Dude I’ve been looking all over for videos about this and this is super super helpful. Thank you for taking the time to make this! Excellent work.

[@philiphart6688]

Great episode, and very methodical work. I did in fact buy one of your V1 boards, and soldering the 0603 LEDs was quite a challenge. But it's still working to this day!

[@spikekent]

Great work Brian. Always great to see your videos. But you're right to only do them when you're in the mood 👍

[@Colin_Ames]

It’s good to see another video from you. Every one I have watched has been interesting and informative, so I hope you have regained your enthusiasm. Take care.

[@ingmarm8858]

Nice video thanks Brian.

[@SimpleElectronics]

What a journey! Thanks for sharing!

[@JeremyCook]

Thanks for the video, very informative!

[@AJB2K3]

Thank you for making this vid as i was a bit confused about the twitter post.

[@guatagel2454]

Nice idea, thank you!

[@BeckyStern]

Thank you Brian, I learned a lot!

[@UndernetSystems]

Love you Brian! Hope you're doing well :)

[@charlibiris]

This is very cool!

[@ElectronicSupersonic]

Very helpful thank you

[@MrRealgamer777]

Very interesting video with a lot of great information, thanks for sharing! I wonder if someone at Kingbright screwed up and just couldn't be asked to fix it, that footprint difference could lead to some infuriating errors.

[@tinygriffy]

IDK how many you would buy, but maybe you could contact the manufacturer directly .. sunled for example makes nice plcc z wing leds, or maybe they can tell you who is selling these in numbers you need ? I found very cheap side view stuff on ali express, but I guess you already looked there. that was me searching for bottom view leds for 40 minutes ;)

[@GnuReligion]

I have used a 3d printer to create a cavitated overlay of shapes for LEDs, then covered the top with wax paper for a diffused effect. A flexible FDM material called TPU, in "natural" color can also make a good diffusing glove or sleeve for a PCB, while giving the item protection. One single 0.4mm layer of TPU is almost impossible to tear or permanently deform with bare hands. Know you are fixed on reverse mounting though.

[@ChongMcBong]

cheers Brian :)

[@roidroid]

Can you get tiny little half-spheres of metal (or mirror-coated plastic), to glue ontop of each LED? To reflect back as much light as it can from the side-mounted LEDs. I used to see all sorts of interesting shapes of beads when i was working with them, if i see anything that could be used for this i'll try to remember to send it your way. A half-sphere might not even be nessesary, perhaps a simple strip of metal would be sufficient: Soldered to the board just on one side then roughly folded over the LED. Think of it as similar to a PCB shielding can, but much simplified. 13:27 If you're going to use hot-glue then that makes it even easier. Put a dab of hot-glue over each soldered LED, then stick a tiny square of tinfoil/alfoil ontop of the still-hot glue. The glue should keep the foil well away from shorting anything on the board. You may be able to use *foil confetti* instead of foil (so u don't have to cut it youself). You can also get self-adhesive *foil tape* of various very-thin widths which is used for finger-nail art. edit: another option is to cover the entire back of the finished PCB with a sheet of *metallised mylar* (ie: space-blanket or potato crisp packet), plastic side inwards so it doesn't short out. I think potato crisp packets might even be coated in plastic on both sides (so they can heat-seal the packets). I love foil, it's a very useful material.

[@AdityaMehendale]

The "cheap" 0804 or 1206 LED could also be reverse-mounted if you had a cut-out. Agreed, it is difficult to get a square cut-out, but you could dog-bone this. This causes a problem: No diffusion. A simple & cheap solution would be to stack a "dummy" PCB (so 2 PCBs in total); considering that FR4 is reasonably cheap, this would allow _any_ diffusion, crisp shadows (from copper, rather than solder-mask) and an easy construction of the "main" PCB - heck the two PCBs could even be single-sided.

[@Magic-Smoke]

Did you consider making the boards thinner so the leds could be brighter and use less power/lengthen battery life?

[@imbw267]

Have you tried using laser cut diffused white acrylic? It may be a suitable replacement for the hotglue pattern, and is scalable.

[@Soren_Marodoren]

A couple years ago I used an LED from Agilent that where available in 5 different colors. 4 of them had a dot indicating the cathod. But on the red one the dot indicated the anode. Not good at all.

[@tinygriffy]

I guess the "PCB only" way is desired here, but what about 3D printing a tree shaped "diffuser" where the PCB clips in and mounting "normal" LEDs .. not an option ? Protection for the PCB ... uniform look ... might also provide a better stand ... safer for small children (if battery contained in print).. ghostly afterglow after turning it off (if you have the right filament ) Just my three thoughts.

[@Rok_Satanas]

you could use those leds from China and have PCB A all the electronics and the led mounts and hole for the them, and the have PCB B be in front of that and be the "cosmetic" one, and simply glue them together. And like John Macrae suggested below, make the front PCB thinner. That would cost more in PCBs but it could work just fine, if you are planning to make a lot of them.

[@MarcioT]

How about using filament LEDs of the sort they use in old fashioned bulbs?

[@ianhora3892]

Hi Brian, What is the part number of the LED at the 9:20 mark? Thanks, Ian

[@eddyfontaineyoutu100]

Use conventional mounting led's and two pcb's "sandwich mounted" ? Cheers

[@anshchawla566]

When is going to be next live 🥺🥺🥺🥺

[@jamess1787]

Don't pull a mickmake!!!!

[@BrianLough]

Jlcman? Maybe I could be his trusty sidekick, lcsc boy!