SparkFun Forums

[iled]

I'm working on modular LED display, composed of LED tiles, each of which will require 256 throughole RGB LEDs. What's the easiest way to solder all of them on? There are 4 pins per LED, so I'd rather avoid doing it by hand.

[leon_heller]

Get a PCB assembly company with a wave soldering machine to do it for you. It won't be expensive.

Leon

[Philba]

Unless you can find a wave solder machine, I think you'll just have to hunker down and hand do your 1K leads. Get some really good ventilation otherwise you'll be breathing some nasty fumes for a long time.

I figure if you get efficient, you can crank through the whole thing in about 2 hours. pre trim the leads and you should be able to do a lead in 5-6 seconds. That works out to be 102 mins. Figuring in breaks and fussing - 2 hrs. Your stuffing time may be longer though.

Had you designed with SMT LEDs, you could use a skillet, hot air or reflow oven.

Phil

[FartingMonkey92]

Hmmm. I would cut out a square of wood/MDF and drill an array of holes for the LEDs to stand in, maybe with a few small stand-offs to raise the board from the LEDs very slightly.
Plonk the board over them and start soldering...

[Philba]

how does he line up the leads? I'm not getting your idea at all.

I was thinking hand stuffing the LEDs (with pre trmmed leads) and they should just say. at worst case he will need to bend the leads slightly. Unless the holes are exactly the same as the leads where they exit the body of the LED, there will be some spreading/contracting of the leads which will keep them in place.

[FartingMonkey92]

Okay, i forgot to mention the other way you could do my idea...
Put the LEDs through the board then plonk the wood block over them and flip over.

Plausible?

[muntron]

Okay, i forgot to mention the other way you could do my idea...
Put the LEDs through the board then plonk the wood block over them and flip over.

Plausible?

Not just plausible, this is a long standing recommended method. It is important for the jig to be accurate, the eye is easily distracted by out of place LEDs

[bigglez]

I'm working on modular LED display, composed of LED tiles, each of which will require 256 throughole RGB LEDs. What's the easiest way to solder all of them on? There are 4 pins per LED, so I'd rather avoid doing it by hand.

Are these SMD/SMT or TH LEDs?
SMD/SMT = Surface Mount Device/Surface Mount Technology
TH - THrough Hole

Are you attaching them to a PCB or protoboard?
If it's a PCB does it have PTH and solder mask
PTH = Plated Through Holes?

Farming this out to an assembly house is the only
sane way to avoid the work.

[propellanttech]

I'm working on modular LED display, composed of LED tiles, each of which will require 256 throughole RGB LEDs. What's the easiest way to solder all of them on? There are 4 pins per LED, so I'd rather avoid doing it by hand.

If you switch over to SMT and the board size isn't very large (no bigger than 10 inches x 10 inches) we can assemble the boards for you.

James L

[noptical]

Here's something I thought, someone with more experience please correct me if that wont work.

Apply solder paste on the holes/pads on solder side of the pcb. Place all the leds through the holes, there will be enough solder paste around the leads. Flip the board (place something over the leads so they dont come out when you flip it) and use a hot air gun to heat the pads where the paste is. Trim the leads.

[leon_heller]

You won't create reliable solder joints that way.

Leon

[noptical]

You won't create reliable solder joints that way.

Leon

Well at least it'll save you a lot of time and you can always fix the joints with a soldering iron, faster than soldering 1000 leads one by one

[bigglez]

Here's something I thought, someone with more experience please correct me if that wont work.

Apply solder paste on the holes/pads on solder side of the pcb. Place all the leds through the holes, there will be enough solder paste around the leads. Flip the board (place something over the leads so they dont come out when you flip it) and use a hot air gun to heat the pads where the paste is. Trim the leads.

Excellent Idea! Hopefully someone will try this and report
back here.

The problem is going to be displacement of the solder
paste when the leaded parts are inserted into the holes.

Another issue is the paste may cause bridges (shorts) if
capillary action doesn't pull it to the pads. Watching SMT
soldering by IR or hot air shows the molten solder is
pulled onto the pads as it liquifies.

There is a company that makes "solder washers" which
can be placed over a leaded part and then melted down.
It would be tedious to do this for all leads one at a time,
but the mass soldering by IR or hot air would pay off.

There is a strong case here to redesign in SMD/SMT only.

[Philba]

There is a strong case here to redesign in SMD/SMT only.

good point, as I mentioned last Friday...

[macegr]

You can make your own solder rings by winding solder around a thin rod in a tight coil, then cutting along the length of the rod.