Lpc2000

Sean wrote:

>Those look pretty neat and easy, but really it's not a tough task soldering 
>.5mm QFP on your own.  For any surface mount components it's extremely 
>useful to have a nice binocular microscope, around the 7x magnification 
>range.  One on a boom is much better.  Once you have that, it's pretty easy 
>to do all SM work, check for shorts, etc.  Even without it's not terribly 
>difficult, but you'll need some sort of magnifying glass to at least check 
>the work.  Placement isn't difficult either, especially once you've done a 
>few and know the tricks.  I'd probably say that 99% of all experienced 
>electrical engineers CAN solder 0.5mm QFP on their own, not the other way 
>around.
>
>Considering how you can get a prototype double sided board made for like 
>$30 USD (roughly 4"x6" in size), you may be better off designing a module 
>yourself with all required supporting circuitry (osc, regulators, caps, 
>rs232, usb, etc) that can be reused for multiple projects, you can likely 
>get 4 modules out of a single 4"x6" sheet.  Just a thought.
>
>  
>
I agree, you can hand solder 0.5mm but it is tough to keep from getting 
solder bridges between pins, or the absolute worst is when you get a 
bridge "behind" a pair of pins!

I'd done handsolder down to 0.8mm, then hot-air pencil + syringe paste 
applicator at 0.5mm.  This is with a commerially made board with a 
solder mask.  What I use now is a toaster oven and mylar stencil (thanks 
to SparkFun!).  It is the absolute easiest way I've found to build SMD 
boards!

My current board has 140+ SMD components on it, ranging from 0805, to 
SSOP, to 0.5mm TSSOP / QFP.  It only took 2hours to setup, paste, apply 
parts and reflow using the stencil + oven.  I would not think to attempt 
a board as complex as this (and as small) by hand, you always get too 
much paste or it won't flow right and it bridges...

I use Advanced Circuits (http://4pcb.com), check out their $33 special: 
full silkscreen, paste / solder mask, and resolution down to 7mil.  
After many years of etching my own boards, I let someone else do the 
dirty work.  :P

Myself, I'd be very leary of the claims that the Schmart Board people 
make.  Soldering SMD _is_ a PITA.  BTW, I do have a 10X / 20X binocular 
microscope, 20X makes it possible to solder jumper wires to the 0.5mm 
pins (now, if my hands would only stop shaking).

Regards,

TomW



-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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