AVR-Chat

arhodes19044 wrote:
> I will look into drag soldering!  I have the binocular loupes 
> covered.  I have a really nice set of loupes.  I can see the detail 
> well below my ability to manipulate it, and they have good field of 
> view.


It amazed me when I started as to how your muscles etc 'servo' to what 
your eyes can see. if you have the magnification for the eyes, the hands 
can do some extremely fine work. On protos I often ended up soldering 
bits of kynar wire onto fine legs of IC,s to add a quick logic analyser 
test socket or the like.

Cheers

Don










> 
> THe soldering is the trick.  I will definitely try it with old 
> computer cards.  I have enough of those!!!
> 
> -Tony
> 
> --- In AVR-Chat@yahoogroups.com, Don Ingram <don@l...> wrote:
> 
>>>One alternative already suggested is an adapter such as 
> 
> a "surfboard" 
> 
>>>or similar.  The problem is tha amount of square inches required 
> 
> for 
> 
>>>the conversion from smt to 0.1 spacing pins.  All those pins 
> 
> take up a 
> 
>>>huge amount of space!!!!
>>>
>>>I just do not see how I can reliably solder all those tiny SMT 
>>>connexions.  I would have to use my loupes for sure.  ALso a new 
> 
> iron 
> 
>>>with the 1/64" tip....
>>>
>>
>>Tony,
>>
>>Hand soldering a TQFP is dead simple...  as long as you have the 
> 
> knack.
> 
>>Have a look at the app notes on the Metcal site for the mini-hoof 
> 
> tips & 
> 
>>their use in drag soldering. Pace may also have an app note for 
> 
> their 
> 
>>'mini-wave' tip series. Googling 'drag solder' brings up a 
> 
> squillion hits.
> 
>>Once you have an idea of the drag soldering technique as used with 
> 
> blade 
> 
>>& concave tips you will find it quite easy to work with these 
> 
> packages. 
> 
>>It will take a little practice but you can get this by removing 
> 
> and 
> 
>>refitting packages on old computer cards. Pull them off with a 
> 
> paint 
> 
>>stripper gun & then clean up & refit them with your drag 
> 
> technique. 
> 
>>Using controlled heat it is quite possible to do this cycle > 20 
> 
> times 
> 
>>on an FR4 PCB without lifting tracks.
>>
>>There are a number of concave tips available for common brands of 
> 
> iron 
> 
>>these days. There was a video of the process on the net ages ago 
> 
> but I 
> 
>>don't know where ( too much red is bad for the head Ned! )
>>
>>Key things are:
>>1. Good heat control
>>2. Tons of flux
>>3. Good vision - use bino glasses or even better a cheap stereo 
> 
> microscope
> 
>>It is much faster to fit a TQFP than it is to hand solder a 64 pin 
>>adapter package using thru-hole.
>>
>>
>>Cheers
>>
>>Don
> 
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>  
> Yahoo! Groups Links
> 
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