[sdiy] Starting with SMT hand-soldering
ic1 at bell.net
Fri Oct 29 05:00:30 CEST 2010
How about de-soldering ?
For chips you flood with solder and soak up with wick, or the butane torch method ?
For chip rx/cx's you heat one side and slide the iron in a sweeping motion to force the part loose ?
Is there a more elaborate way to do this ?
On 2010-10-28, at 7:33 PM, Dave Manley wrote:
> On Thu 10/10/28 1:58 PM , "Jason Tribbeck" jason at tribbeck.com sent:
>> On 28 October 2010 21:47, Dave Manley wrote:
>> On Thu 10/10/28 12:17 PM , "David G. Dixon" dixon at interchange.ubc.ca
>>>> I'd like to try my hand at laying out and
>>> hand-soldering an SMT board and> thought I'd stop in here to see what
>> advice I
>>> could get from those that> have done it.
>>> Go see Rick Moranis about getting yourself shrunk...? :o)
>> Short of doing that:
>> For chip resistors/caps: holding the part with the tweezers, solder down
>> one end. Move on to the next component, only soldering down one end of
>> all the caps and resistors, then make a final pass soldering the other end,
>> and touching up as necessary. Some people will object to this, but I find
>> this is the fastest.
>> For leaded ICs: solder down one corner, then solder down the opposite
>> (diagonal) corner. If all the leads aren't perfectly lined up on the
>> pads, adjust the corners until you get it right. Then solder all the
>> other leads, using lots of solder flux, dragging the wetted iron while
>> applying more solder, solder all the leads on one side in a single pass.
>> With practice you can get very good at this and not need to do much touch
>> up, or cleanup with solder wick. There's no reason to solder one lead at
>> a time! Don't do it! :-)
>> This reminded me of something: I use a pair of tweezers which are normally
>> closed for the resistors/capacitors, which means you don't get too tired
>> doing a lot of them. But I also only solder one side at a time (I also try
>> to tin the pads in the same orientation so I don't need to spin the PCB
>> around too many times).
>> The technique for chips described above does work very well, but it did
>> take me a while before I was comfortable doing it - for a while, I found it
>> easy to do 1.27, but difficult for 0.8, and then easy for 0.65 and smaller.
>> I think it's because the 0.8mm is close to my soldering iron tip size, and
>> I couldn't drag the solder properly. However, after a bit of practice, I
>> think I've got it cracked.
> The other thing I like to do when putting down chip resistors/caps, is to put a little bit of solder on one of the pads first. Then you only need two hands to put the part on - step one put the solder on, step two with the tweezers slide the part into the pre-soldered pad that you're heating with the soldering iron. If you pre-load one side of all the component pads with some solder, then assembly goes much faster.
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