hot air rework station dc jack suggestions

[pcpete]

We bought an AOYUE int968A a while back. We do a few dc jacks / month and some other lite soldering. We have been experimenting with the hot air portion for dc jack removal. I suspect our technique is horrible. Any suggestions on technique would be appreciated. I also have a few specific questions.

We have need setting the temp at about 435 C for both the hot air and the iron, is this to high?

We try to shield the are not wanting to heatup with a bit of foil, is this good, bad or do you have a better suggestion?

I noticed today on the board we were about to start removal of the jack(hence my post), there are surface mount "things" on the back side, do we need to worry they will also heat up and fall off?

 

[Larry Sabo]

The temp sounds alright but these hot air rework stations are so unreliable and inconsistent when it comes to temp readings. My Gordak requires around 475C to do the job but my W.E.P. 858D produces a lot hotter air at that setting, so I reduce it to around 385C if that's what I'm using. Using flux is key, as it seems to really affect the melting process. I would mask off adjacent SMD components with Kapton or aluminum tape to prevent them from being dislodged, if they are very near the jack. Haven't had any problem with components on the underside, but be sure they are not touching anything as you work on the top side. Take your time and let the MB around the jack heat up, but if it starts to go black you risk having ruined it. Don't force the jack off if it's not ready. It should almost fall off on its own once the solder is liquid.

 

[Krynn72]

One thing I've found that helps a lot, no matter what method you use to actually remove the jack, is to add new solder before removing it. The new solder has a core of flux built into it (rosin core) and removes the oxidization on the original joints. The new solder tends to go molten faster than if you rely on the original solder only as well. I don't use the hot air method too often because I found it to be a complete pain in the butt, and much prefer using something like the Hakko 808 and just remove the solder joint-by-joint. Still, I'd rather use hot air than a copper wick I suppose.

 

[acesdeals]

Stay away from Aoyue, go with Atten instead

Yes by putting new LEAD solder not lead free it helps lower the melting point

 

[RChadwick]

I've got a hot air station, but get much better results using a soldering iron for DC jacks. As mentioned, just add some solder. I usually blob it so it covers all the leads at once, and it should just drop out. A gentle pull may help. Often I put a big blob of flux on, as it helps the solder connect to the leads, and transfer heat better (Just don't forget to clean up the flux later). The quicker, the better, as the PCB can be damaged by high heat. If you're having problems, and don't intend to reuse the old jack, you can carefully clip off the visible leads, carefully cut apart the jack, and get to any hidden leads. Sometimes it is easier to remove one lead at a time.

 

[pcpete]

Blob it to cover all the leads at once? That sounds a bit insane(just giving you a hard time). I personally have never even considered doing more than one at a time with an iron.

 

[RChadwick]

For removing the jack, it makes sense. If you heat only one lead, the others still hold the jack in. Then, you have to fuss with it, rocking it out slowly, and flexing the board under heat, which often leads to permanent warping. Remember, more heat for longer time = damaged PCB. Adding lots of solder and flux, and blobbing it across the jack's leads, I can remove most jacks in 10 seconds. A quick shake or wipe usually leaves it ready to solder in a new jack, but sometimes I clean up with solder wick. Solder behaves much better with flux. Same thing goes for soldering as well.

 

[Krynn72]

There's a special type of solder called ChipQuik I've used before specifically for that purpose. You need to use some solder wick afterwards to make sure you soak up as much of it back up as possible before using regular solder again, but ChipQuik is great.

 

[RChadwick]

I almost mentioned ChipQuik. It's great stuff when you need it, but you have to be careful to clean it all up when doing DC jacks. ChipQuik is a solder that melts at a lower temperature than normal solder, but it is also significantly weaker. If you don't do a good job removing the ChipQuik, the replacement DC jack may not last very long before the solder cracks. Again, I'm nutty, but I use a special Silver alloy solder for strength.

 

[Krynn72]

Again, I'm nutty, but I use a special Silver alloy solder for strength.

Got a link for the Silver alloy you use? Always interested in bettering my process.

 

[RChadwick]

Looks like I lost my notes. I found a chart that had PSI ratings for different solders, and one silver alloy was better than most of the others. When I find it again, I'll post. I think it was 96.5% tin and 3.5% silver.
BTW, I remember being surprised at the strength of regular 60/40 lead solder compared to others, considering lead is so soft.

 

[Larry Sabo]

Looks like I lost my notes.

This table perhaps?

 

[gadgetfixup]

Nothing much to add but our technique is mask off smds in the area, put board, jack down, on a pre-heater (you'll be amazed how much this helps) running about 100-120 C, use some good flux and hit all the joints with lead solder once the board warms up. Grab your hot air gun with the right size nozzle, typically we use a 10mm, something that will hit all the joints at once is the goal. We run our hot air stations around 320-330 and don't think we've ever been over 370. Typically the jack will fall off in under 10 seconds. I would never use chipquik for a jack replacement. Too great a chance of it flowing on to some nearby smds and then you'll have a mess. Also as mentioned the melting point is low and retention is poor. If you need to use it be sure to clean it all off.

What we found most helpful over the years is quality flux, solder and wicks. We've been through a lot of manufacturers over the years but now have very specific vendors to produce consistent results. We found most people or videos telling you what sort of supplies to purchase didn't have much experience and typically offered poor advice. Some of the most highly recommended supplies I wouldn't give you two cents for.

That's our method for what it's worth.

 

[pcpete]

Thanks guys. I have learned a lot of good as stuff.

Do you guys have any tricks to cleaning out holes? We have both used wicks and a sucker along with an iron. The holes tend to be the hardest most time consuming part for my. On another forum a guy said he cleaned the holes exclusively with hot air only, blowing them clean. I had no luck with that method.

 

[RChadwick]

That wasn't the chart I found, but looks like the same information, maybe better. I believe I chose 96.5% Tin and 3.5% Silver, as it was strong, but not as brittle as some of the others. Also, I usually add a dab of glue.

I just couldn't solder without flux. I don't worry about the mess. I put on plenty, and clean it up with alcohol and a brush when done. Looks as good as new, except it's likely better. If you can, compressed air is a quick way to blow off the alcohol and flux.

As for the holes, my methods are:

Push a toothpick through the hole when the solder is melted. Lick or wet it first if you want, but it's usually not important.
Solder Sucker
Tap the board gently while the solder is still melted. It will splash, but often leave the hole empty. Wear safety glasses. Seriously.
Solder Wick
Make sure you use enough heat, and use flux
Worst case, drill it carefully

Also, make sure you have a good sized iron. If it's adjustable, it's usually best to turn it all the way up. Copper ground planes suck the heat away from what you're doing, and if you don't hit it with enough heat, you won't fully melt the solder. Again, you don't want to do this long, but if you have a high enough heat, you won't need to. Sometimes a pre-heat helps.

I can't stress enough the importance of flux when soldering. Most rosin-core solders have flux inside (The rosin), but I find it's often not enough. DON'T use the acid flux for plumbing. With flux, solder just behaves. I can solder a 100+ pin Surface Mount chip in a minute by flowing the solder across all the pins. With flux, the solder balls where it's needed. Without, it acts like a glue-like paste that covers all the pins.

Soldering well takes experience. If you have some old motherboards hanging around, they are great for practice. Try removing and re-installing components.