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Soldering tips for tiny connectors

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radiodude

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I am trying to solder a tiny connector onto a PCB board. There are 30 contacts on this connector, each contact is 0.2mm thick. I am having a very hard time 1) lining up the connector on the board & getting it to stay there and 2) soldering the actual wires on the connector to the traces on the PCB.

I was told I could just throw a bunch of solder over the wires and then just suck up the excess solder with some wick. However when checking for continuity, there's always breaks and I have shorts as well (and I also tend to melt the plastic a bit which probably adds to the problem).

What advice can you give for soldering small connectors with very thin wire contacts onto a PCB? The PCB boards are kind of expensive & I only have a limited supply left (less than 5). I've "destroyed" 3 boards so far by only trying to solder this connector on.

The connector is an XF2L-3035-1. I'm a noob at soldering in general so this soldering task is very frustrating for me...but I have to learn [and quick!].

Any tips will help, thanks.
 
Treat it as a surface mount device, brush the tracks with liquid flux, then carefully position the connector on the board. Next tack each end of the connector in place with a very fine needle pointed soldering iron. Then brush liquid flux over the top of the contacts, and flow solder them by drawing a special spoon shaped bit loaded with solder down the contacts - or you could individually solder each pin VERY carefully with the needle point bit.

Notice this requires three specialised items you probably don't have?, not having the correct gear is probably making your problem worse for you, along with your lack of soldering experience.
 
what he said. also i find it helps if you have jittery hands to press the butt of your iron to your chin since at least for me my head is allot more stable.
 
My Soldering Tips

I use to have to solder surface mount Processors approx (50.8) or less apart. A water soluble flux along with the tip Nigal suggested is the best way it's called floating.

Basically what happens is the tip of the Iron will automatically keep the droplet of solder attached to the tip as you brush over the intended area to be soldered. It is attracted to the heat and clings to the tip if you have enough flux on the area to be soldered it will dispense it evenly.

I always tilt my work so that it has to pull the solder from the tip of the Iron up onto the pins (Remember to do this you'll also be tilting the tip of the Iron slightly making a V shape to keep the solder droplet closer to the work your dispensing it on. You'll see the action as it happens then it will just be a matter of heat to much or to little.

(Try to practice on some old circuit boards removed from discarded electronics?) leave the component on the board and see if you can make appear close to the same as before you had tried. (Just a suggestion)

If you get it sticking between two locations then apply more flux and clean your tip add more solder to it. When cleaning off old solder I never use water & sponge to my tip either bronze type of Brillo or I just shake it making a big mess on the floor sounds bad but it is better than cooling the tip and adding o2 to the combination.

("For me only" I learned this from an Old Timer)

I could do this process soldering a 128 pin processor every two minutes including the alignment they looked as good as machine almost undetectable.

One last thing if you have pre fab boards you will have solder on the board where surface mounts go. I always use a ribbon braid over the area first so that the processor will lay flat and still as I pre solder some pins to hold it in place.
 
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killivolt said:
I just shake it making a big mess on the floor sounds bad but it is better than cooling the tip and adding o2 to the combination.

("For me only" I learned this from an Old Timer)

I always used to have thin spashes of solder on the floor wax at my bench. :rolleyes:

killivolt said:
One last thing if you have pre fab boards you will have solder on the board where surface mounts go. I always use a ribbon braid over the area first so that the processor will lay flat and still as I pre solder some pins to hold it in place.

I do this, but I am still not very experienced in surface mount soldering as soldering in general. I have found that pad preparation by pretinning and then copper wicking to remove excess surface solder to absolutely necessary. The value of liquid flux can't be overstressed.

If I leave the tip of the iron on just a few milliseconds too long, I get a solder peak, or "lick" like the top of the connection, just like a soft ice cream cone. I don't get this lick if the joint is made very quickly. It's as if the solder changes characteristics in just those few milliseconds. I use 60/40 or 63/37 solder. Does anyone have a tip on how to prevent this peaking, maybe by changing solder Pb/Sn/Ag mix or iron temp?

The surface tension of solder gets problematic at small scales. The solder blob on the tip of the iron is so big compared to the spacing between conductors.

Bob
 
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Yup I know !

Bob Scott said:
I always used to have thin spashes of solder on the floor wax at my bench. :rolleyes:

Then you are the type of old timer I'm talkin about.

I do this, but I am still not very experienced in surface mount soldering as soldering in general. I have found that pad preparation by pretinning and then copper wicking to remove excess surface solder to absolutely necessary. The value of liquid flux can't be overstressed.

I had never seen it done until I worked at a Military Contractor. (surface mount soldering)

If I leave the tip of the iron on just a few milliseconds too long, I get a solder peak, or "lick" like the top of the connection, just like a soft ice cream cone. I don't get this lick if the joint is made very quickly. It's as if the solder changes characteristics in just those few milliseconds. I use 60/40 or 63/37 solder. Does anyone have a tip on how to prevent this peaking, maybe by changing solder Pb/Sn/Ag mix or iron temp?

I think of metal urge and the dissimilarity of metals and impurity's going to the surface I believe it's in escapable.
Just shake it and apply new or use the Brillo to wipe it off I know it seems a waste but I'd rather do a good job.(And all I can say is flux flux flux)

The surface tension of solder gets problematic at small scales. The solder blob on the tip of the iron is so big compared to the spacing between conductors.
Bob

Yep and when they started designing in these new processors the really small guy's I was outta my league.

It was tini tiny tips and one at a time carefully not to burn it up.

By the way it used to piss off my bosses to have all that around my bench, but I was the only guy who didn't trash $50.00 processors. My jobs were 300 run jobs @ %100 no losses. Befor that they were losing % 30 of their boards. Due to poor manufacturing. After 2 years I had the floor from the front side to the end and I hand picked my best workers. Both QA & QC. Nothing left the building unless my hand touched it last.
 
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The number one thing I'm missing is flux. And I'm also not tinning my tip. What I'm doing is heating up the pins and then just globbing solder in there & wicking it up.

I do have a microscope & the iron is the one in the picture below. I can definitely get the tools that I need, but I still need the right technique. Can you elaborate more on the 'flow soldering' technique?

**broken link removed**
 
Pace actually call it 'wave soldering', here's a picture of a Pace bit

**broken link removed**

The bit has a spoon shaped depression, which you fill with solder, and you simply pull it along the fluxed pins to solder them all in one operation, it really works incredibly well. The REALLY important thing is the liquid flux, it's the flux that makes it work.
 
OK, I will try it out. Can't seem to find that tip for this Weller iron, so I'll just have to improvise with a nail file.
 
radiodude said:
OK, I will try it out. Can't seem to find that tip for this Weller iron, so I'll just have to improvise with a nail file.

How do you file a circular depression with a nail file?.

Also any remotely recent bit is going to be coated, filing it destroys the coating.
 
Have you tried wrapping thin ( 28 or 30 guage) solid wire around the solder iron tip before applying power? You keep the tip away from the board, avoiding short-circuiting traces with unpredictable results. I don't do SMT soldering, I read about this method in one of my many magazines.
 
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