• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

anyone here with surface mount soldering experience?

K

kevinf2090

Senior member
So I've been ask to build amplifiers using surface mount soldering techniques. This is also my first time doing any surface mount work. I think I have gotten the hang of it and can pretty much solder everything pretty quickly. The only problem for me right now is soldering the amplifier on the board. The amplifier has 6 pins. I usually am able to solder all the pins down, sometimes accidentally bridging two of the pins but I was able to get it off using soldering wick. I have no way of testing the amplifier right now so I am worried about heat damage from the solder. How much heat does it take for an small 6 pin amplifier IC to become damaged? I was able to successfully test continutity across the input and output pin but I don't think that really says much about the IC.

Thanks in advance for the help.
 
Well the temp we use is about 750f. And whenever I'm soldering, the iron doesn't stay there longer then maybe 2 seconds at a time. Is this bad? I'm not sure how I would use a heatsink during soldering.
 
Last edited:
kevinf2090 said:
Well the temp we use is about 750c. And whenever I'm soldering, the iron doesn't stay there longer then maybe 2 seconds at a time. Is this bad? I'm not sure how I would use a heatsink during soldering.
Click to expand...

The heat sink goes between the solder point and the component. I grew up in the bad old days making my own pcb's and doing projects from Popular Electronics. Truthfully, the only way to learn is to do it. We used multimeters and did a lot of checking as we went along. It's an old technique that isn't used much except by hobbyists.
 
i was able to test my resistors and they were still showing the correct value after being soldered. but how do i test capacitors, inductors and ICs (amplifier)
 
I linked a few sites to help out. The point I was going after is you will make mistakes and you will cook components. IC's really can't be checked until you complete the circuit unless you have an oscilloscope handy.
 
so if an IC is cooked or overheated from soldering, is there any visual way to tell? also i've had to solder brass sma connectors on the boards. after soldering it on, i noticed that the entire board got pretty hot/warm. would that damage anything? because there is a lot to solder on the connector to the board, it would make sense for the board to heat up though wouldn't it?
 
kevinf2090 said:
so if an IC is cooked or overheated from soldering, is there any visual way to tell? also i've had to solder brass sma connectors on the boards. after soldering it on, i noticed that the entire board got pretty hot/warm. would that damage anything? because there is a lot to solder on the connector to the board, it would make sense for the board to heat up though wouldn't it?
Click to expand...
Short of actual melting or bulging IC's, there's no visual way to tell. In general, for the type of home projects most folks do, the board would have to get very hot indeed to actually damage the components. When soldering brass or other heavy leads to a pcb, you might want to attach a copper lead extender/ring to the lead first before soldering it to the board. Many of these skills can only be learned through experience. Getting it right the first time is a miracle. Don't give up, don't rush, clean your board and soldering tip often. Take frequent breaks. Have fun!
 
can you explain a bit more about attaching a copper lead extender/ring? i would do a google search but i'm not sure what terms to put in
 
are you using flux? i usually tin one of the pads, dab flux on the whole pattern, hold the device with tweezers, use the pencil iron to attach the tinned pad to the device. this fixes the IC so you can solder the rest of the pins. the solder should be sucked right into the junction.
 
I'm usually just using the flux in the solder itself. But yeah I also use the same method. I put solder on one pad then reflow the solder onto one pin to hold it in place. It's just that when I'm adjusting the IC while trying to reflow the solder, I worry that the IC may be getting too hot.
 
Lay an aluminum strip across the leads between the body of the IC and the solder pads. In the bad old days of thru-hole I used to have a bent-nose needle plier set that I used to hold the pins near the body of an IC.

Typically when I solder a smallish multi-pin device - I lay down flux on the board. This boils and gets between the pins and helps keep shorts to a minimum. When I was doing production line repairs I was to the point where I could replace a 18 pin small package SMT part within a couple minutes. First since the part was bad I would lay down solder over all the pins, shorting them all out. Then use my small tweezers to hold the edges and melt all that solder on both sides. The old part lifted right off. Then clean up the board with the solder vacuum until it was back to bare pads. Then clean it with alc, a dot of cement to hold the part, some flux, and I'd get all the pins at once with one swipe of the iron and the solder.

An amplifier IC is intended to get hot so it shouldn't be tooooo bad. Your bigger enemy (though probably not as bad as say a memory chip or a flash module or microcontroller) is static.

Try a drop of goo under the device to hold it fast (rubber cement works but they make stuff for this)
 
also i forgot to ask. Would I be able to tell that I just killed a component with static? would I feel a shock or is it usually too small to feel?
 
kevinf2090 said:
also i forgot to ask. Would I be able to tell that I just killed a component with static? would I feel a shock or is it usually too small to feel?
Click to expand...

you probably won't be able to tell if there's static damage until you power it up. even then static damage isn't black or white, there may be only a few specific situations where you can observe it.

honestly, don't worry about it too much.
 
I have replaced many surface mount parts, including 200+ pin TQFP's. A 6 pin IC is pretty easy to replace. You'd be surprised how much heat parts can take. A few seconds should be fine. Liquid flux works a lot better. For best results, wash the board. You can be a lot more liberal with the flux when you know you're going to wash the board. You get much better reflow with liquid flux. It is less stressful for the part because you dont have to apply heat for as long. I've washed hundreds of boards in a regular old sink with just water and a toothbrush, and used compressed air to dry them.
 
That's pretty subjective, depending on the type of ICs they can become damaged with no temperature at all with electrostatic discharge when touching them. Wouldn't hurt to look into ESD Control.
 
Last edited:
I hope that is a wrong about the temp you are using , 750C is too hot. Lead temps for soldering on most parts is suggested to be 300-400C max and no more than 10 seconds at those temps.
If you are doing a lot of surface mount parts get rid of the soldering iron and get a hot air station. You can get a decent one off ebay for about $100 . Then just put your paste solder on the pads , put the part on top and heat and you are done. No risk to parts or the boards.
http://www.ebay.com/itm/2IN1-SMD-SO...076?pt=LH_DefaultDomain_0&hash=item5ae18b62f4
 
Last edited:
Modelworks said:
I hope that is a wrong about the temp you are using , 750C is too hot. Lead temps for soldering on most parts is suggested to be 300-400C max and no more than 10 seconds at those temps.
If you are doing a lot of surface mount parts get rid of the soldering iron and get a hot air station. You can get a decent one off ebay for about $100 . Then just put your paste solder on the pads , put the part on top and heat and you are done. No risk to parts or the boards.
http://www.ebay.com/itm/2IN1-SMD-SO...076?pt=LH_DefaultDomain_0&hash=item5ae18b62f4
Click to expand...

I'm really late to this so I haven't read all the posts, but I whole heartedly agree with this. Using a hot air station and solder paste makes the job a real snap. You will want to inspect the soldering job afterwards to make sure that there aren't any bridges between densely pitched pins, but on the whole it is a much easier and effective method.

In one of my labs that I worked at we had a jury rigged soldering station where there was a small CRT TV with a video camera using a macro lens. This allowed us to view the work up close for easy inspection. Other than that, most of the advice that I would offer has already been given. Use a nice set of tweezers to manipulate and hold the parts. Don't forget to have some soldering braid handy to suck up any excess or fix a bad solder job.
 
Born2bwire said:
In one of my labs that I worked at we had a jury rigged soldering station where there was a small CRT TV with a video camera using a macro lens.
Click to expand...

I did something similar. You can get webcams that look like they have a fixed lens, but if you take them apart what you usually find is the lens is adjustable by turning it one way or the other. They usually are threaded and have a bit of paint applied to the threads to hold them in place. The one I have is a logitech I got off their discount site for $20. I can adjust the lens to the point that a single pin on a 120 pin device fills the screen.
 
I would not know what to add to all these posts. Just that when you remove small smd components (capacitors, resistors, inductors or SO-8, SOT23-x or SC-70 casings for example) with a solder iron, use a good quality solder tip and apply lot of solder to heat up all pins at once. Then you can just scoop the component of without damaging the solder pads. If you never done it, please practice first on old defective boards.

Since i do not have as much time as i would like to have, i have delayed the buying of a hot air station over and over again : The Aoyue 852

product_01-90852-a.jpg


This one is not expensive and good for home soldering of SMD.
Get some good quality flux. or get solder paste with good flux.

I like this one because it is a small syringe. Beware, the flux in the solder paste does degrade over time :

42350734.jpg

It is CR44 from Edsyn. Available from Farnell. And with old fashion lead.

http://uk.farnell.com/edsyn/cr44/solder-paste-in-syringe-10g/dp/876768?Ntt=876768

Also, do not forget to place the solderpaste syringe in the refrigerator with the syringe closed if you do not use it. Maybe it is not needed, but i have good experiences with this method.

Caution !

Use proper ventilation to remove the flux and solder gasses. It is very bad for your health to inhale this stuff.
 
Last edited:
You must log in or register to reply here.

TRENDING THREADS

Back
Top