Dummy Chips and PCB for Soldering Practice - Page 1
Forum section: electronics / projects

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: October 03, 2014, 02:29:27 am
content: I'm working on a project that uses an MCU in a 100-pin LQFP with 0.2mm pin pitch. The thing looks daunting to hand solder.Before I try with the real thing, I'd like to get some dummy chips in this form factor along with a PCB with pads to match to practice soldering. Anyone know of any sources for parts that match this requirement? The chips don't need to be working chips as I'll just be using them for soldering practice.

author: marshallh
author_rank: Unknown
timestamp: October 03, 2014, 02:48:29 am
content: Just get a spare of the same chip if it's not cost prohibitive.Amkor sells mechanical samples but they are extremely expensive and hard to purchase.I've not heard of 0.2mm QFP... at this point you may be better off doing BGA.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: October 03, 2014, 02:57:56 am
content: Oops... Typo in my original post. The pin pitch is 0.5mm, not 0.2mm.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 03, 2014, 10:53:09 am
content: http://www.ebay.com/itm/Practice-PCB-and-Components-/120731121523?pt=LH_DefaultDomain_0&hash=item1c1c22b773

author: Kjelt
author_rank: Super Contributor
timestamp: October 03, 2014, 01:33:30 pm
content: http://www.printtec.nl/contents/nl/d442_Kit's_voor_handsolderen.html

author: Rufus
author_rank: Super Contributor
timestamp: October 03, 2014, 02:16:22 pm
content: Quote from: Sal Ammoniac on October 03, 2014, 02:29:27 amIf you want daunting try a 0.4mm pitch part... on a 0.5mm pitch footprint.

author: calexanian
author_rank: Super Contributor
timestamp: October 03, 2014, 03:26:36 pm
content: Get afold of a couple small prototype boards. They are cheap on eBay and just find the cheapest IC you can in a scimilar package and use leaded solder. Preferably with the most active flux you can find. Such as Kester 44. You will need to clean it but it will flow much more easialy. Also remember extra flux helps so glop it on. Drag soldering is effective once you get the hang of it.

author: sacherjj
author_rank: Frequent Contributor
timestamp: October 03, 2014, 03:51:21 pm
content: Cheapest might be to get some 0.5mm FPC connectors. Once you can solder a string, you can do that on 4 times along each edge. Just make sure to get the chip lined up well.I find that the easiest to do hand soldering this small is to drag a small solder paste stream about 10 mm from the tips of the pins. This makes it easy to run the tip of the iron through it and get just a bit of solder and touch it to a pin. Drag soldering didn't work for me with 0.4mm connectors, as there was to much close copper that was unable to drag solder without it wicking into where I could not remove it.

author: rob77
author_rank: Super Contributor
timestamp: October 03, 2014, 06:35:17 pm
content: older PC mainboards had some small pitch quads on them - those are good for some practice . desolder with hot-air (even a hot air paint strip gun will do the job), clean up the PCB (flux + solder wick) and solder the chip back.drag soldering works for me - and don't worry about solder bridges - just remove them with a solder wick after the chip is soldered.