[sdiy] Hand soldering TQFP packages

[Seb Francis]

Peter Ullrich wrote:
> You only need a normal (not SMD) soldering iron - but also a SMD one can be 
> used.
> The important part is a special flux paste: RMA 04-HV (Stannol and other 
> companies have it).
>
>   

I can't find anything like this on the UK RS website.  I do have a (no 
clean) flux pen, but it's definitely not a paste - it's like a thin 
clear liquid.

I found these 2 products
http://www.rapidonline.com/searchresults.aspx?style=0&kw=85-6276
and
http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=45354701&N=401
http://www.farnell.com/datasheets/21998.pdf

Neither are described as "pastes", but they both look like they are 
sticky, as opposed to the stuff that comes out of a flux pen which is a 
thin liquid.


> - First you have´fix the IC on two edges (no matter if you connect some pins 
> together!) - just be sure to fix the part on the right place.
>
> - Then put a the flux paste on all end of the pins (the end of the pins and the 
> rest of the copper needs the paste). 
>
> - Take your soldering iron (temperature a little bit higher than normal - 380 
> degrees celcius are ok) and start from one corner (but not one of the two 
> corner where you fixed the part!) and deliver enough solder and move with 
> constant speed over all pins on that side to the end of the row.
> The fluc paste garantees that the solder can flow under the pins AND that the 
> excessive solder flows back to the soldering iron and so to the next pins. When 
> the soldering iron leaves the pin there is normally no bridge between pins and 
> you get very nice soldering joints!
>
> With this method my collegue soldes a 208pin 0.5mm part in about 3 minutes 
> including optical control and maybe one or solder wick corrections.
>
> I also tested this method by myself and it works fine!
> The flux paste is not cheap but worth every cent!
> You can buy it f.e. from RS-components...
>
> I hope that helps you soldering your chips.
>
>   

Good tips, thanks :)

Seb