PCB trivia – can you spot the short?

Ah the joys of manufacturing …

This one drove me crazy, no short at a close inspection. But I was determined to find it. I ended up desoldering almost all components off thinking the short is under some cap or resistor, but the short was still there. I had to pull the microscope to track it down. Here’s a shot of the PCB through the scope. Can you spot the short?

PPM visit and Quad IVc/4000c pick and place demo

In an effort to deliver truly meaningful and comprehensive content, I will write a few articles about pick and place machines and SMT assembly, after many months of trial and error with various methods, in hope to help others who may want/need to get into SMT equipment and assembly. The focus will be on pick and place machines, my observations, what I learned in my prolonged research into pick and place machines over the last year, what some people say, what some companies end up choosing and why, what to look for, what to run away from, etc.

I first saw the article about the Quad IVc pick and place on Ohararp.com and was curious to see this machine up close.

We visited PPM (Precision Placement Machines) some time ago and was able capture a few of the cool things we’ve seen there. This video shows a demo run and feeder setup on a Quad 4000c (Quad IVc upgraded to Windows 7).

I really took a long look at this machine and that’s why I took a day off to go out there (they are truly out in the country). Unfortunately there aren’t many resources on the web about these machines, at least not high quality pictures or videos, so I hope this will change that at least a little bit. The visit was very much worth it and the great staff showed us around and throughout the PPM facility. There’s too much to say about the visit and I hope to make some time to post more pictures later so here are a few more photos of the tour. Later I will expand on our observations on the Quad pick and place.

For now I will just post this video showing the Quad 4000c in action. It illustrates how the machine dispenses paste, places a range of components and finally how a feeder is setup:

From china, with love: bad solder paste

Recently I was running out of solder paste and I’ve bought some chinese paste to try out from a (very) popular online electronics outlet. I think somewhere in the reviews or in one of the tutorials they say they actually use that paste internally so I got confident and the price was right (I guess… even though I later found the same paste on dx.com for under $5), about $14 for a jar of 50g which would last a long time. Great I thought, I’d get it in time to assemble more boards, without the insane shipping delays from china, so I ordered and got peace of mind.

A few days later I got it and I assembled a batch of boards with it and peeked through the microscope to inspect how it reflowed. Here’s what I saw:

bad_solder_paste

Holy cow! What happened? Tons of tiny balls of solder stuck in tons of solder paste residue. Not one of my best days, but certainly memorable. Continue reading