[time-nuts] Vaperware Parts and pulse stretching circuits

[Burt I. Weiner]

John,

What you and I do for SMT type IC's is pretty much the same.

Several years ago the wife of a close friend was 
in the re-work business with a home setup.  What 
she taught me was to first line up one of the 
corner pins and tack solder it down.  Then do the 
opposite corner, center the pin and tack solder 
it down.  Do that with all four corners, taking 
care that the pins are properly centered before 
tack soldering them.  Once you've got the four 
corners properly in places, then go and center 
the remaining pins; depending on the size of the 
chip, this might require either a microscope or 
very pointy eyes.  Once all the pins are properly 
centered, flow solder over all the pins.  At this 
point shorting all the pins together is not a problem.

Once you've flowed soldered across all of the 
pins you need to slurp up all of the solder with 
a fine pitch SolderWick.  If done correctly you 
will wind up with all of the pins properly 
soldered and centered.  The next step is to 
remove and flux using Denatured Alcohol.  Once 
that's completed, inspect for any possible shorts 
or pins in the wrong place.  If all looks good, 
cover your eyes and power it up.

I have done the above one time on my own and to my utter amazement it worked!

Burt, K6OQK


At 04:41 AM 4/25/2020, you wrote:
>I do have a microscope (cheap Chinese unit, 
>maybe $400 with articulated arm and the works) 
>and it does make things much easier.  But as 
>long as you can see the work, you can do the 
>job. It's not that hard to do small pitch 
>parts.  I usually do the best I can soldering 
>individual pins, knowing their will be bridges, 
>then clean up with solder wick and *lots* of 
>no-clean flux.  You can never have too much 
>flux.  I've found a 1.6 mm chisel tip is a good 
>all around size for SMD work, though I have a 
>0.8 mm chisel available for when things get 
>tight. The hardest part is getting the first 
>couple of pins tacked down so the part is square on the pads

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
biwa at att.net
K6OQK