RE: RE: SMD soldering?

Andre'

You're very welcome and Glad I could help. I was worried I may have given too much info. 

Keep in mind you will make a mess at 1st :). And by no means is it an easy task, but with patience's and if you have never used external flux you will be amazed at the results. When soldering surface mount IC you can't use too much external flux. 

Something I didn’t mention was when you clean, if you use an acid brush, clean in the direction of the leads. This way if one of the leads didn’t solder you won't bend it out of shape. Once clean then use your explorer or xacto knife to ping the leads to make sure you have a good solder joint.

They make a canned flux remover which was great when it was triclorafloraethain (sp) but they went green and it takes a half of can to clean 1 ic. But this may be good for the final cleaning. Also if I'm not mistaken, no clean flux is water base and it take alcohol to clean rosin fluxes.


-----Original Message-----
From: owner-cbm-hackers@musoftware.de [mailto:owner-cbm-hackers@musoftware.de] On Behalf Of "André Fachat"
Sent: Sunday, November 01, 2009 07:50
To: cbm-hackers@musoftware.de
Subject: Re: RE: SMD soldering?

Hi Scott,

I'm soldering SMDs onto newly made PCBs (my own design, for some new boards of my selfbuilt 6502...) The PCBs got solder resist (solder mask, Lötstopplack) on them, I didn't trust myself enough to not use it...

I did solder the other ICs with 1.27mm pin distance (74xxx logic, RAM) with a small soldering iron and small solder and it worked fine.
Even with traces running between the pins. I did use a magnifying glass though... :-) (and some desoldering braid(?) to get superfluous solder away).

Only the other ICs I have are even smaller. I'm new to soldering with flux, but it seems I'll have to give it a try.

Thanks for your advice!
André

-------- Original-Nachricht --------
> Datum: Sun, 1 Nov 2009 07:27:52 -0500
> Von: "Scott" <rylos@charter.net>
> An: cbm-hackers@musoftware.de
> Betreff: RE: SMD soldering?

> Andre'
> 
> Make sure the glue that held down the old IC is removed, you can do this
> by
> over curing it with your soldering Iron. Then prep the pads, use flux and
> leave a small amount of solder on the pads. This solder will make the
> joint
> for you.
> 
> I then tack down opposites corners of the IC using just enough solder on
> the
> iron to make it conduct. If the IC's pins are not bent most of the other
> legs will fall in place. If they don’t, carefully move them over with a
> sharp pointed object, I usually use an Explorer (dental tool).
> 
> Once you have everything aligned. Soak the pins will a good flux. I still
> prefer rosin flux because no clean evaporates too fast. Now, hold the pin
> down with the Explorer and touch it with your Iron. If you have enough
> flux
> on the leads you shouldn’t have to worry about bridging the pins. So
> don’t
> be overly concerned about touching more than the leg you want to solder. 
> 
> Once everything Is tacked down, clean then reapply flux and re-solder
> using
> the explorer to get that clean finish. Then take the explorer or exactor
> knife and carefully run it between the legs of the Ic to make sure there
> are
> no bridges. Observe with a magnifying glass. Clean again and your done. 
> 
> Of course make sure you bounce back and forth when soldering, left side of
> the chip to the right side, this way you won't overheat the IC. And most
> important, your Soldering iron tip temperature should turn to a nice
> golden
> brown after solder is applied. If it turns the flux in the solder black
> then
> you are way to hot. 
> 
> Anyway, all steps are important. But To answer your question, I normally
> just tack down the corners first. 
> 
> -----Original Message-----
> From: owner-cbm-hackers@musoftware.de
> [mailto:owner-cbm-hackers@musoftware.de] On Behalf Of "André Fachat"
> Sent: Sunday, November 01, 2009 06:31
> To: cbm-hackers@musoftware.de
> Subject: SMD soldering?
> 
> 
> Hi,
> 
> I know some of you do SMD soldering. I did already solder 1.27mm distance
> packages, but now I have to solder some 1.0 or .8mm pins - and I find it
> quite difficult to position the SMD part correctly. I only have normal
> pincers as help. I solder one pin and by resoldering that pin I can
> actually
> correct the position before soldering the other pins - but that seems
> difficult with those smaller parts.
> 
> What do you use to position those SMDs? Do you have vacuum pincers /
> airpicks (or whatever they are called)? Or do you use other tools? Like
> glue
> to keep the part in position when positioned? 
> 
> Any help appreciated
> 
> Thanks
> André
> 
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