Hi. I have a Atmega 8A IC fixed on a circuit board. I want to access 13;14 pins of it. It is TQFP package IC. Very tiny legs\pins. I tried to solder the wire and the melted solder wire spreads on other pins.Is there any alternative of solder ? I searched on google and found Wire Glue.But is not available in INDIA for online order Anyone know where I can get the wire glue in Delhi or online purchase ?

To solder TQFP, u should get a copper wick and use that to absorb excessive solder, still the best method. Or take a blob of sodler on your iron, and drag it across the pins. It works very well, doing pins individually is not possible.

Also pre tin the wire , and dont take any more solder on your iron, and just fuse, that should work

Quote from: MohitJindal on October 10, 2012, 09:48:57 AM
.Is there any alternative of solder ? I searched on google and found Wire Glue.But is not available in INDIA for online order Anyone know where I can get the wire glue in Delhi or online purchase ?

If this a one - time requirement for on-off project, I would recommend you to go to a road-side Cell phone repair guy. They have SMD Re-work soldering station and can safely solder these components.
If you need such soldering in the near future, Yash's suggested method is pretty de facto in the DIY circle. search you  tube and you can find tons of Video Blogs.

@ujwaana... That's a good idea... Cell phone repair guys have the tools needed... I didn't think of that....but get a guy who has the equipment... Some use normal iron to work....its just years of mastery that enables them to solder with precision.

Ohh yes.. If you use the DIY method make sure you use a POINTED tip, and not one of those flat tips or chisel tips or such... Because they hold way too much solder on them.

Quote from: yashodhanp on October 10, 2012, 03:16:03 PM
. Some use normal iron to work....its just years of mastery that enables them to solder with precision.

Taught by my Dad,  been soldering since Class 4th or so!! But SMD soldering is a different beast. Need the right tool,  right technique. Its too frustrating to spoil a costly chip or a 'Sample' chip not available locally.

So how did your soldering go?

hunt youtube and google.. some people do SMD soldering via "microwave Oven". i cant locate the thread, but there is lots of content on google search..

Metal in any microwave is not a good idea, and it may damage the chip..

The best way to solder smd components at home is to either use a toaster or an OTG. Just pre-tin the solder pads and the legs. To make it easier first dab the places to be soldered with flux. Now place the component you want to solder on the pads with the correct orientation and place the whole pcb into the oven or toaster and heat it just until the solder melts Another option is to use heat gun.

Be careful using oven. My oven destroyed a board last week. My mistake was that I relied on the temperature display in the oven. It was showing 170degC and I was waiting for it to hit 200-220. Next thing, I saw it melting. The actual temperature was atleast 50deg more than what it displayed.

You are messing with quad boards now ?   Or was this some other fun new tronics hobby ?

No it wasn't a quad, it was an Allwinner A10 board. Would be nice to have that much processing power in a quad. The chip is cheap enough compared to the ones used in quad controllers.

What happened ?  A tablet or PVR or something like that die on you ?

Sorry this is going OT !

Yes, came out of a misbehaving tab.

Ovens are probably the worst way to solder smd, as they will also heat up the plastic casing etc. and ruin electronics

Reflow soldering is the standard manufacturing process for almost any PCB you see nowadays. When it comes to BGA, oven is the closest solution a hobbyist can get. All components are built to withstand this process. Problem is when you go outside the recommended temperature profile which is what happened to me by mistake.

Reflow soldering is another beast, the reflow ovens are precise to 2-3 degrees. Normal ovens are simply no good. Also some reflow soldering processes use infrared lamps instead of ovens

Dont use any normal oven if you not mastered in reflow oven.
Cheap and best idea is to visit cellphone repair guy.
With Flat tip regular soldering iron, you have to use surface tension of metalic solder with plenty of flux. And of course tilted PCB ("near about 90 Deg) to use Gravity to wash out the excess solder with help of Bit tip.It's just practice. But Excess flux is must for detaching excess solder from joint. Later you have to wash out the flux with thinner.
While opening, Generally we use enameled solder wire which pulls up the legs one by one from PCB. We solder one end at any joint and passes the wire through narrow space from soldered pins and ceramic envelop. Then start heating & pulling open end pin first keeping tension at 90 deg. Melting of solder instantly pulls up the pin from PCB.
You can have youtube for them.

Hello,

To me this seems like something wherein we need specifics. In my opinion the multi layer boards are different class and need to be treated differently. during manufacturing, on any large production bed, the SMD assembly is all computer controlled and components are laser oriented.

If we are now to replace any faulty component, this can be done by hot air gun (ideally seen with mobile repair shops), ideally the SMDs do not have much space and tolerence for the conventional soldering irons. Some might still do that, frankly, on repair side most of the boards have signature checks to find the faults/faulty components.

Microwave certainly can not replace this as, while doing so we may accidently moving other SMD components too, hence after SMD mount, only the local part replacement with directed heat gun is preferred in professional industry. Also the compinents and tracks have sufficient metal to damage microwave's magnetron easily.

Also, some complex boards have many sandwich layers which have different heat sensitivity levels before they burn out.

thanks

No, not a microwave oven, unless you want to start Diwali celebrations early. Only use a conventional oven with heating elements. As far as the rest of the comments from different people, to each their own, depending on their own knowledge, expertise and risk appetite.

Quote from: RotorZone on October 18, 2012, 12:25:24 PM
No, not a microwave oven, unless you want to start Diwali celebrations early.

Lol!!!

Quote from: RotorZone on October 18, 2012, 12:25:24 PM
No, not a microwave oven, unless you want to start Diwali celebrations early.

Hahahasha: well said