Soldering hints

[Charlie]

Thanks again Zetr0, I had a feeling there was going to be no alternative...

...as it happens after my last post I remembered my wife has a 'hot air gun' that she sometimes uses for enameling stuff. Bodge a nozzle & bob's your uncle I guess.

Ok, next probably daft question:

Resoldering surface mount components - I've seen videos on various ways to do this where the pins stick out if you see what I mean but none on how you do the packages where the pins are underneath (where there's no room for the tip of an iron).

My guess is if my new found 'hot air gun' actually works you could tin the feet by hand, place the package on the contact pads, apply hot air & wait for the solder to run...
...a good plan?
or
Am I looking @ buying some solder paste too..?

Oh, yes - d*mn lead free solder! Horrid stuff, I think I'll stick with poisoning myself...

[TheCorfiot]

@charlie

If you are concerned about your hot air equipment (Fnar )

Use this method. Using a sharp stanley knife, run the blade along the top edge of the chip legs (by it's casing) Until you gently cut through.
Then remove the casing leaving all the soldered legs in the air which you can then remove with a very small tipped iron & tweezers

TC

[Charlie]

Thanks

[Zetr0]

@Charlie

okay, I think i see what you are trying to do now...

first run the hot air over and around the component in a small circular motion, using tweezers gently nudge the component from time to time, eventually it will come off...

Important ALLOW TO COOL ON A METAL SURFACE

do not force cool the component by dropping it in water or that IC will be destroyed... allow to cool for 5 minutes on a bit of tin or something, I use a bit of tin plate cut out (shaped into a thin tray) from a dead PSU.

Now to get a component like this to BOND properly back to its new home, first flux the area liberally, then using wick clean off all the old solder... (hot iron at 360c should do) just dont leave the iron in one place to long..

Now again throw a load of liqud flux on the area, drop the temperature of the iron to around 250-280c pending on the thickness of your solder, now... re-solder all the contacts required with small beads of solder... add a load of more flux.. swamp the area

place component in the proper orientation... using tweezers to steady the unit... now Hot air... again low air, medium heat... move the air around slowly, eventually the surface tension of the molten solder will pull the unit into place....

NOW.... allow it to cool for a few moments.... now clean it with everything you have... allow to dry.... now test the component!

[TheCorfiot]

Doh,

I must be half asleep today, My tip was fine to remove the "dead component" but not much use for transferring a good component

Zetro is the JEDI Master for this

Where's the Coffee

TC

[Charlie]

Thanks, I guessed it would be something like that - I suspect the details will save me.

My equipment:
-Wife's 'Heat-it' craft tool.
Looks like a very small hair-dryer - bloody hot!
You can tell it's for 'girls' - there's a do not use as a hair-dryer logo on the side.
-Small bread tin - the baking variety.
-Needle-nosed pliers - they'll do...
-Flux pen - I guess that'll have to do too.

So far...
One dead simm into the tray.
Balance 'hair-dryer' within 1cm of the chips to remove.
Go to fridge for beer.
Pour beer..
Back to baking tray & 'hurrah' two mobile chips.
Carefully remove chips & bin them (the bad ones)
Drink some beer.
Proceed to remove the other good chips from that side of the 'donor simm'.
Drink some beer.
Remove the two bad chips from the simm to be fixed.
All has gone well.
Finnish beer in celebration of a job well-done.

As a bonus nerves now steadied for the 'tricky bit'.
My God those pads look small, glad I got some thinner solder - maybe another steadier or three will be required...

[Zetr0]

okay Charlie.... assume the position and give us PICS!!!!

[Zetr0]

okay.... knowing some of the type that frequent this board, I think its best to say that (a) the position is behind the camera and (b) pictures of the hacking involved.

[Charlie]

Ok, photo's in a bit.

[Charlie]

Here's the photo:

Click for a biggun.

Ignore the mangled end of the 'donor simm' - that was yesterday.

Note the 'do not hair dry' logo - I'm almost tempted to change my Avatar.

[Charlie]

Hey, treble post!

Where was I?

Newly surface-mounted chips:


Try in Amiga, no go - *sigh*

Quick fondle of the packages revealed another hot one.

Ho, hum,

Out with the old:


And in with the new:



...I am your surface-mount soldering God!

Bow down and praise me as your Almighty!!!

Ahem, pardon me while I wipe the froth from my mouth...


...yes, it seems to have worked. Isn't that nice?
My thanks for all the advice.

[Zetr0]

Anyone that can SMT with a childs hair dryer gets Respect!



well done Charlie, some good work indeed

so its all working now?!

[Charlie]

As the dog says:
Oh-Yes!

Sorry for the slightly erratic posts - I've been quaffing a 'steadier-or-two' between stages for most of the evening...
...to help my nerves you understand.

[Zetr0]

Some awesome work there my friend, if i dont sound too condecsending I would say proud as well!

truly great work!

now take all the steadiers that you need/want job well done

[TheCorfiot]

@charlie

Nice one mate.......... Success


TC

[Charlie]

(^$*%^£$££& computer!!!

I'm kind of pleased with myself for ressurecting one of my 128mb simms & learing a bit of surface mount in the process - thanks for all the kind advice chaps...

...Having tested it in my A1200 I plugged it back into one of my RiscPCs (Firefox consumes a lot of memory you know) - all still good...
...reboot to the smell of magic smoke escaping...

D*mn computer's popped the simm AGAIN!!!
(This is also the computer that allowed a suicide woodlouse to explode it's HDD a few months back)

Frantinc swappage of simms - Ahhh, it still works.

So I've spent another evening re-re-replacing chips - no sucess this time...
...I think I've had enough practice now.

If I can be bothered tomorrow I'll pull all the chips from the 72pin simm & cannibalise yet another 168pin simm & start from scratch.

So here's my contribution(s) to the Soldering Hints thread:

1) A craft heat tool hairdryer thingy is + a loaf tin is enough to do SMT.
2) For God's sake don't put the simm you just repaired back in the b*stard computer that popped it in the first place!

[Charlie]

128mb Simm working again - Oooo, getting lots of practice:
Next?
Convert 2x1mb VRam modules to 1x2mb VRam module. (more useful).

Piccies:
1) 2)

3) 4)

1) Two indentical modules..?
2) Nooo, one has no chips on the other side, but all the traces are there - ah, ha! More practice.
3) Here, I've prepared all the pads with flux, then blobs of solder, then more flux as kindly outlined by Zetr0...
...Now I thought doing this with the 72pin simm was fiddly - apart from the pads for what I assume are SMT capacitors (you see I really have no idea what I'm doing) the other pads are about 1/3 the size of the last lot - hell fire! The end of my iron looks enormous in comparison, this looks impossible!
[ Show youtube player ] to the rescue! This was REALLY easy - I wish I knew about this when I was fiddling with the 72pin simm...
...as it happens I just used this technique to tin the pads in preperation to using hot air for the soldering - why?
-I discovered the drag technique by accident so it never occoured to me to do it all in one go.
-When you've got a technique that works, is trying a new technique really a good idea with something you don't want to break? Besides the package pins are so small I'm not so sure I could do it with what I've got.

Then:
-Place the SMT 'capacitors' & hot-air them down - in the process nicely evening up the pads ready for the chips.
-Hot air the chips down one at a time.

4) The finished article:
-Top: How the reverse of a 'real' 2mb VRam looks.
-Middle: The donor 1mb VRam.
-Bottom: My attempt - not bad, eh?

So why am I posting this?
-To hopefully add something useful to this thread after all the help I've had.
-To encourage others to have a go: 2months ago I was a clueless soldering iron butcher, last week I'd never tackled anything to do with SMT, now look!
The more of this I do, the more I realise being able to solder is going to be very useful - how did I cope all these years..?



Oh, and to ask for some help...
...Um, depite the 'prettiness' of the above it doesn't acutually work.
Having checked things the job's a gooden - no bridges, no poor contacts, no burning...
...In a fit of lazyness I robbed the SMT 'capacitors' from a donor 72pin simm as it was easier...
...I suspect with hindsight I should have used the ones from the donor VRam...
...is this a fair assumption?
Do the 'capacitors' again, buy with the ones from the donor-VRam & all will be well..?
Please don't tell me they also have +/- ends - how on Earth would I tell..?

[xc8]

hi ya all.

check this site, has some soldering tips..

http://www.circuitrework.com/guides/guides.shtml

[Charlie]

THanks - looks a very useful site.

[JackTheKnife]

I'm looking to buy a soldering station. Any tips, etc?