Soldering an smd on an old mobo

[Somerandomtechyboi]

 

Basically someone seems to have borked a repair in the past and now the M_BIOS chip is not making proper contact with the pads so the board is effectively unusable even though i can post if i short the B_BIOS at exactly when it rolls over from code 02 to CE where itd usually get stuck

 

now i wanna have a crack at resoldering this thingy and fixing the board cause i have actually gotten it to a functional state with some solder paste before it dried up (made it to windows) and it seems like a pretty trivial fix

 

For the equipment i think id need

Heatgun

Kapton tape

Tweezers

Solder wick

Aluminium foil

Solder paste

Flux

 

I already have the bottom 3 so just need to buy the heatgun tape and tweezers

 

As for heatgun im thinking of just buying some <10$ heatgun with the highest wattage i can find which seems to be around 1600w though im not sure if i wanna choose

Spoiler

This

Spoiler

Or this

the only diff i see between them is wattage (1500w vs 1600w)

 

 

as for questions

 

Anything else to consider when buying a heatgun? reason im choosing a high wattage one is to have a crack at desoldering chipsets (i mean you can reflow gpus with a heatgun whose to say you cant desolder bgas with one)

 

and how would i go about actually desoldering and resoldering the bios chip itself? Cause currently the way i see it going is just flux on the bios chip, desolder bios chip, clean the residual solder with some solder wick, put some solder paste, put bios chip back on, heat till paste turns into solder, then cleanup excess with solder wick

[Heats with Nvidia]

Please don`t use a heatgun for this! You will melt all the plastic around it. Just get a Pinecil, TS101 or even TS100, a finer tip and some good flux and solder it by hand. You could also look up drag soldering and use a bigger tip to remove the excess solder.

 

Also please use a lot of flux, then its really easy.

[Somerandomtechyboi]

9 minutes ago, Heats with Nvidia said:

Please don`t use a heatgun for this! You will melt all the plastic around it. Just get a Pinecil, TS101 or even TS100, a finer tip and some good flux and solder it by hand. You could also look up drag soldering and use a bigger tip to remove the excess solder.

 

Also please use a lot of flux, then its really easy.

Cant i just use aluminium foil + kapton tape to deflect any stray heat?

 

currently im trying to do this as cheap as possible and im also gonna have a crack at some bga rework with the same heatgun just for shits and giggles

[Heats with Nvidia]

1 hour ago, Somerandomtechyboi said:

Cant i just use aluminium foil + kapton tape to deflect any stray heat?

 

currently im trying to do this as cheap as possible and im also gonna have a crack at some bga rework with the same heatgun just for shits and giggles

You can do that and it might even work, but using an soldering iron in this case is just much easier and less damaging to the board.

[Needfuldoer]

Yeah, you should be able to rework this with just a soldering iron with a chisel tip on it. Clean the area with isopropyl alcohol and a toothbrush, then use flux and touch the pins up with fresh solder. Once you've reflowed all the connectors, clean it again with alcohol, the toothbrush, and swabs to get rid of the flux residue.

 

SMD does not automatically mean you need hot air! Sometimes that just makes a bigger mess.

[Somerandomtechyboi]

3 hours ago, Needfuldoer said:

Yeah, you should be able to rework this with just a soldering iron with a chisel tip on it. Clean the area with isopropyl alcohol and a toothbrush, then use flux and touch the pins up with fresh solder. Once you've reflowed all the connectors, clean it again with alcohol, the toothbrush, and swabs to get rid of the flux residue.

 

SMD does not automatically mean you need hot air! Sometimes that just makes a bigger mess.

I dont have a solder station setup yet and my cheap irons are kinda trash

 

So unless i can just use a 2$ 60w iron or something id still be inclined to go heatgun especially when i can stop stray heat by just using a bunch of aluminum foil and i can also have a crack at bga rework

[Simon Hosa]

All SMDs which have soldering pads on sides are solderable with classic soldering iron. My first SMD prototypes were soldered only with soldering iron by hand. After that I bought a hot air soldering station, you can better concentrate heat and control the whole process while repairing. Oven is also a good thing but not for this. As I said you can solder any SMD with exposed pads. It depends only on your skills. This is an easy and quick job. Just take the soldering iron and apply soldering alloy to the tip of your soldering iron. Make quick alignment of microcontroller and PCB then tip and solder one side of microcontroller (Doesn't matter if there is shorted pins) let it a little bit cool down after that solder other side. If you have some shorted pins you can just take regular copper wire, apply a little bit of fux to this wire and then use it like a sponge for tin bridges. I am personally preferring paste KOKI alloy TIN 62%, LEAD 36%, SILVER 2% with 10% of flux inside. This is the best soldering paste I had. I recommend alloys with lead for beginners but also for professionals because of fast oxidation of lead free based alloys in low temperatures. Then clean with IPA you can help it with an ESD brush.

 

Reflowing BGA is just reflowing, but soldering is something else and it is not that easy you need special pattern for tin paste or tin balls designed for this. Please show me your BGA chip. Is it really a BGA package?  (I think that I had this board revision 2.1 but without BGA parts)

 

PS: I also started with soldering iron made in CCCP and reflowing station from China for about 36€ as a student. These pro tools make your job easier, more productive and comfortable but cheap Chinese stuff are also just fine for hoby use.