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How to solder properly

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I realize that there may be better places for this post, but I put it here to maximize exposure..

I couldn't help wondering how many diodes have been destroyed due to bad soldering, so I decided to make a thread to give some tips on how to get perfect solder joints when constructing your laser or driver, and soldering in general.

Rule #1: [highlight]Soldering takes practice[/highlight]. Don't get too frustrated if your solder joints aren't perfect. They'll get better and better with time, and frustration WILL lead to messed up joints. If the joint doesn't look good, it isn't. Redo it. I know that with laser diodes too much heat can be a bad thing. Your best bet is to solder laser diodes while in a heatsink of some sort (like an Aixiz module or even the original sled heatsink). This will help draw the heat away from the diode. Keep the amount of time that the iron is in contact with the diode as short as possible. I recommend no more than 5 seconds MAXIMUM. Preferrably more like 2-3. If you haven't successfully made the connection after 2-5 sec., be patient and wait for the diode to cool completely, then try again. If you don't like the looks of the connection, use desoldering braid (more on this later) to undo the joint and remove any excess solder.

Rule #2: [highlight]ALWAYS tin the tip of your iron with solder before using it.[/highlight] To do this, heat up your iron and once it is hot run a bead of solder around the tip of the iron. When the tip is covered with solder, take a wet sponge (ALWAYS have one handy) and wipe the excess solder off the tip, leaving a shiny surface. This will help keep the iron clean and keep your solder joints strong. Also wipe down the tip after EACH and EVERY connection. In order for a connection to be strong, it needs to be made with a clean iron. Solder also flows better when using a clean iron.

Rule #3: [highlight]ALWAYS tin the leads and wires that you will be soldering before making the connection.[/highlight] You'll find that if you coat the leads and/or wires with a very thin coat of solder before making the connection you'll be able to make the connection in less time. This is because the solder is already there. All you have to do then is hold the leads/wires together and heat them up. The solder will melt and "voila", you have a perfect connection.

Rule #4: [highlight]ALWAYS use just the right amount of solder[/highlight] (this gets easier and easier with practice). Using too much will lead to a sloppy joint and possibly a bad connection due to too much flux preventing connection or shorting due to the excess solder bridging between connections. The solder joint should look clean and have a SHINY finish. If the solder joint has a dull silvery finish, it needs to be redone. ALWAYS make sure that you have the right size solder and iron tip. Using a gauge of solder that is too thick will cause you to be sloppy if you're connecting something small. Using a tip that is too big will have the same results. If you're soldering something small, use small solder and a small tip, and vice versa..

Rule #5: [highlight]If you must undo a connection, ALWAYS use a de-soldering tool like de-soldering braid (also called wick) or a de-soldering iron.[/highlight] Personally I use braid, since it is cheap and usually does a fine job. To use the braid, simply place a small piece between the iron and the joint. When the solder melts, it gets sucked up into the braid so when you lift it off, it leaves a neatly disconnected and de-soldered joint.

As I said before, soldering takes practice. I know that there are some very experienced solderers on this forum, so I welcome anyone to add to this. I may have missed something.

I hope this leads to better connections, and fewer killed diodes..
 

jwc

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Nice tips, ElektroFreak.

I consider myself to be farily good at soldering, but yesterday, I saw someone work with SMD components and his skill totally blew my mind. It was absolutely spectacular.
 
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^Yeah. Surface mount is a real challenge. I only use surface mount components when size is crucial, since my skills aren't the greatest.. I've been known to take a circuit that was intended for surface mount components and build it using standard components if small size isn't too important. Surface mount looks cleaner most of the time, though, as well as being small.
 

hevnsnt

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I REALLY hate to point fingers, but there is some really bad soldering advice going around this board. (by some pretty senior members) I have almost choked on some of what is being said.

Thanks for the great post above! I would also suggest everyone check out:
curiousinventor.com/guides/How_To_Solder
 
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I learned rule #2 ie the sponge, when I was 11. I would say that it is the most important.
My routine is take the iron from the stand, wipe on a nice wet sponge, then dip it in flux befor soldering.

When there is no flux on the tip the solder gets chunky and wont flow. A clean tip that shines like chrome is the rule of thumb I have always followed.

Nice guide BTW, soldering can be tricky when starting out. Its nice to have something to refer to for any beginners interested :)
 

Razako

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One important thing is that you MUST have a good soldering iron with adjustable temperature. I absolutely hate trying to solder sensitive components with one of those $6 cheapo irons from radioshack.

Now I have a decent soldering station and it works much better.
 

Benm

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One thing i am missing a bit: Use the correct type of solder!

For hand soldering, you must use solder wire that has a resin flux built in. Also, i would advise to use lead-based solder whenever available. Working leadfree is possible, but serves no purpose and is much harder to master, especially for the novice.

This might seem obvious to anyone with electronics experience, but from the looks of some attemps i've seen, i'm sure some people use the stuff for plumbing ;)

On the solder-joints-must-be-shiny thing: this can be hard to achieve when working with leadfree components, even with lead based solder. The component leads are often coated with pure tin, which distorts the lead/tin ratio in the total mix, resulting in dull joints. This can sometimes make it very difficult to get nice strong shiny solder joints even if you are doing things right.
 

LRMNmeyer

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Also worth noting is that lead-free solder will be dull when you solder with it.
 

Things

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Yeah do NOT use lead free solder, that stuff is total crap IMO. I find the best stuff is 60% tin, and 40% lead, with a resin core, ive been working with it since I was 6, and it works very well.
 

Hemlock_Mike

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I try to use 63/37 eutectic, rosin core solder. It has the lowest melting point of PbSn solder and has no plastic range on cooling. As pointed above, pretin the wire and lead before application of heat.
I use a 25 watt temp controled iron set at high. That way, I'm off the soldered joint before the diode knows what happened.

ALSO, For connections to LD's which draw under 1 Amp..... I use 26 Awg stranded wire so as not to put excess strain in the small leads. Some pictures I've seen show 20 Awg "solid" wire soldered to those tiny diode leads. DON'T do that :(

Mike
 

Things

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Yeah, you only need to use VERY THIN wire! Even 1 strand could carry a few hundred milliamp, using thick wire is just asking for you to break the pins off!

good tip Mike!
 
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I was just asking where is the best place to buy solder? the place close to me sells thick stuff, and its all lead free :mad:
 

Things

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Weird, most electronics shops sell regular solder, it aint anything special. I don;t buy solder online, so I don't know, sorry
 

Hemlock_Mike

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Try to find .022" dia solder for most work.  I reserve the .010" stuff for SMT jobs. Do not use acid core plumbers solder.

Mike
 




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