POLL: Best way (the proper way) to solder a diode to a circuitboard?

[ZoWhat]

Pictured above is the form factor of the diode and how it will sit on the board.

Best way to solder (?)

(1) put solder ON THE CIRCUITBOARD first then put diode on solder & melt down diode posts into the solder

Or

(2) place the unsoldered diode on the board & then put small droplet of solder OVER the +/- posts

 

[GK3]

Pictured above is the form factor of the diode and how it will sit on the board.

Best way to solder (?)

(1) put solder ON THE CIRCUITBOARD first then put diode on solder & melt down diode posts into the solder

Or

(2) place the unsoldered diode on the board & then put small droplet of solder OVER the +/- posts

That is SMT (surface mount technology). The way industry does it is out solder on the board, place the component, and heat. You must heat to controlled temp to melt solder but not ruin part. Don’t put a huge mountainous glob on the board first or else it will be tough to place the component correctly.

 

[ZoWhat]

I thought this thread would get more traction

 

[hubcap]

are you using leaded solder or lead-free solder. They have different flow temps, with unleaded solder requiring more heat. (Spools of solder usually have composition of alloy on a sticker on the roll. Something like 60Sn 30Pb....anything that has "Pb" on it is, obviously, leaded. Tin and silver are commonly used in lead-free (Sn and Ag)
If you see RoHS anywhere on the board or component, its lead free.

Typically, I clean off the pads with solder wick first. Then apply solder to one pad and attach the diode by heating the pad first (flowing the solder) then placing one lead onto the flowed solder and removing heat.
Then, once the one lead is placed, heat the other lead of the LED first then apply solder to it. Don't dwell TOO long it could melt the phosphor (the yellow stuff on top of the LED) or it could melt the casing that the junction is in. (AKA you could irreplaceably damage it.)

Hard to tell from the pic, but is the circular pad in the center required to be soldered as well (this is typically a heatsink, allowing transfer of heat from the diode junction onto the metallic wafer that its mounted to.)
IF that is the case, its a tricky operation because it usually requires hot air as opposed to a soldering iron.

IF that center, circular section IS required to be a solder connection, let me know and I can give you some tricks on mounting it.....
IF that center circular section is NOT required just follow my instructions above.
(Polarity matters with LEDs....so put it on the same position as it came off....it looks like the wafer has a black line on it to help you along......hard to tell from the pic though)
IF you don't know how exactly it was placed, look closely on the LED itself....usually has a really small dot designating polarity. Im going to ASSUME that if youre asking this question that you already know that but if you don't...….please let me know.

You could test the LED first to see if its still working and I can tell you how, but, lets assume first, that it does work.....

Let me know. I'm well versed in this stuff.


-cap

 

[Carlosroach]

I solder on a daily basis for work. Best practice would be to use solder flux to get an even flow.

 

[Infidel]

I was always taught to place components and then solder, using heat sinks as needed.

 

[hubcap]

the metal wafer its mounted to is, by design, a heat sink. And they work very well. Ask me how I know....


you can successfully do this many ways.
its just my preference because I've been doing it for years with the work I do.
I "tin" ONE pad first (SMALL amount of solder) then place the part with heat still applied to the "tinned" pad. This keeps the solder fluid, and allows for fast transfer of heat to ONE lead. It makes it easier to keep it aligned correctly (Im anal when it comes to placement)
If you put the lead down FIRST then apply solder, the LED itself could skew.

To each their own....Either method would work.

Have a set of tweezers handy will help big time......

 

[hubcap]

Flux works but makes a mess. Have alcohol on hand if you like a clean appearance once its placed.

 

[hubcap]

We might be better help if you let us know what equipment you're working with....
What type of solder gun? (wattage?)
What type of solder? (Leaded or Lead Free?)
Tweezers handy?

etc etc

 

[Carlosroach]

Yeah flux can get messy if you over use it. Easy clean up with alcohol. Pretty much all J-standard methods of soldering call for the use of flux to get the proper flow and solder fillet.

 

[hubcap]

Im gonna go out on a limb and say hes not really concerned with J-Std applications....he just wants it to work, but, you are absolutely correct with what youre putting down.....
(most solder these days are 'hollow core' that have flux already in it.)
easy way to tell is to physically pull a string of solder from the spool and look at it.....hollow solder its easy tell....

 

[lilgrounchuck]

I’ll second for using flux. Apply flux, place diode, apply heat, feed solder, clean up excess. I always get much better results using flux vs not. Just don’t use too much.

 

[lilgrounchuck]

Im gonna go out on a limb and say hes not really concerned with J-Std applications....he just wants it to work, but, you are absolutely correct with what youre putting down.....
(most solder these days are 'hollow core' that have flux already in it.)
easy way to tell is to physically pull a string of solder from the spool and look at it.....hollow solder its easy tell....

Good to know. I haven’t actually purchased solder for about 20 years. I just put together a reef pi and used the stuff I bought from radio shack about 20 years ago. A big spool if solder and a tub of flux go a long way.

 

[hubcap]

oh man, you don't use that pastey solder flux do ya?
what a mess! lol.
just goes to show, there are many ways to successfully skin a cat.

 

[AZMSGT]

First, buy one of these.

get 2m certified

2MMTR

Then you should be able to handle this project.

The hammer and chisel method just is not the way to do this kind of work.

 

[hubcap]

SAME EXACT kit Ive used for decades.
PACE rules.
Weller and Hakko bite. (but work in a PINCH)

I was wondering why my temp wasn't going higher than 76F.....
I worked the pen so hard it needed a replacement.
Notice the black "charring" on the blue grip. Trust me.....I work this thing HARD. LOL.
{I know I know......24Vdc relays and PIC16s.....hiiiiiigh tech stuff. LOFL}

 

[AZMSGT]

SAME EXACT kit Ive used for decades.
PACE rules.
Weller and Hakko bite. (but work in a PINCH)

I used it for a couple years in the USAF, I was 2M certified too.

 

[hubcap]

Good to know. I haven’t actually purchased solder for about 20 years. I just put together a reef pi and used the stuff I bought from radio shack about 20 years ago. A big spool if solder and a tub of flux go a long way.

that old school Radio Shack (shame it folded) solder probably already has flux in it. Pull a strand off and see if its hollow.....might not even need the toothpaste.

 

[hubcap]

Both done by hand. Not a drop of flux.
Using lead free (with the exception of the reworks)
Pay no mind to the cockeyed common mode choke and the crummy rework. I was having an off day
2nd pic is a prototype and had some components that were larger than the pads so it made things tricky, but, it works.

I work with LED strobes on the daily but cant come across any pics.
Philips and CREE are the main brands, but, we test many of them.

 

[Flippers4pups]

To the question of the poll, I've done it both ways successfully. Modded my CBB's several times now.