Hi.

Is hand soldering this device a possibility? Any instruction welcome.

I was thinking of putting together a custom design.

Regards

Martin

I'm not game to try it myself. However, SparkFun have a series of tutorials on soldering surface mount devices with examples and videos:

http://www.sparkfun.com/commerce/tutorials.php

Regards,

Chris

There are many good SMD soldering video tutorials on youtube and the web.  Here are a few of my favorites...

http://store.curiousinventor.com/guides/Surface_Mount_Soldering/101/

http://store.curiousinventor.com/blog/drag_soldering_howto_demo/

I just did this myself a couple of days ago, actually.  I'd never soldered any sort of QFP chip before, so I was rather intimidated by all of the tiny pins.  The smallest surface mount chips I'd soldered before that were SOIC chips with 1.27mm pitch and 24 pins at most. I thought I was going to have to solder each pin with a fine tip on my soldering iron, which would have taken forever, especially since I don't have access to a microscope.  But using a specialized tip, I was able to solder the chip in just a couple of minutes.  I was shocked by how easy it actually was once I'd finished.  I'll no longer be afraid of soldering fine-pitch QFP chips.

The equipment I used:

• Xytronic 137ESD digital temperature-controlled soldering iron (apparently discontinued and replaced with the LF-1600)
• Xytronic "Mini-wave" soldering tip - I think mine is the 44-510607 tip.
• Xytronic 1/64" (0.4mm) soldering tip (44-510603)
• Kester 331 63/37 solder - I've found that leaded solder is easier to work with for prototyping. Substitute if leaded solder is illegal in your country.
• Kester 2331-zx flux pen
• 10x jewelers loupe

The process:

1. Set the soldering iron to around 650 degrees fahrenheit with a fine tip.
2. Place the chip on the board, making sure pin 1 is oriented correctly. Verify with a loupe that the chip pins line up with the pads.
3. Tack the chip in place with the fine tip. I soldered 1 corner pin, verified with the loupe again, then soldered 3 more corner pins. I didn't worry too much about accidentally bridging two pins at this point because I was hoping the mini-wave tip would clean up any bridges. In my case, I didn't have any bridges.
4. Turn off the soldering station, allow it to cool while checking the chip with the loupe carefully to make sure the pins are still centered on the pads and look to see if any pins are bridged.
5. Switch to the mini-wave tip and turn the soldering station back on. While that was happening, flood one side of the chip with the flux pen.
6. Then melt a little bit of solder on the mini-wave soldering tip and then drag the tip across the tips of the pins, holding the iron at something like a 15 degree angle and moving at a speed that would go from pin 1 to pin 25 in about 3-4 seconds. I checked the result with the loupe and found that all 25 pins were soldered with nearly perfect fillets and without any bridging at all.
7. I soldered the remaining 3 sides the same way, then checked the result with the loupe, again finding near perfect fillets and no bridging.

The entire process including time changing tips, inspecting everything over and over again and performing the actual soldering took less than 5 minutes from start to finish.  The actual soldering time using the mini-wave tip was probably less than 30 seconds.

Since then I've soldered another LPC1768 on a second prototype board and had almost as easy a time. I had a minor problem with bridging until I used lots of flux like I had the first time. Even with the bridging problem on the first side until I added more flux, the total time soldering the second chip was under 1 minute because I tacked the chip in place and soldered it with the mini-wave tip.

For production, assuming I don't farm it out, I'd probably go with a proper stencil and purchase a reflow oven. But for prototyping, I will definitely be hand-soldering these chips in the future.

I hope that helps.

That's how I solder fine-pitch devices, I use a Metcal system with a mini-hoof cartridge. Plenty of jelly flux is important for good results.