Really small SMT: Popular packages?

SOT-323 had the most choice earlier in this millenium but your SC-75's are already smaller!

Two-transistor arrays with built-in resistors are the real space-saving step but they can have substantial supply-line problems if you're working in medium quantities and use anything outside the most usual values.

If your designs are "wide enough" there are some transistor and resistor and diode arrays that make great sense. Almost always I see these used in data or address bus situations and I think you fall outside that realm.

Tim.

I've found there are two sub-sot23 sizes I like, which are approximately sot-323 and sot-523. These correspond to sc-70 and sc-75, and sot-523 corresponds to sot-416. The sot-323 part corresponds roughly to a 0.65mm pitch (i.e. the space between the two pins on the same side is 1.3mm); the sot-523 approx 0.5mm. Note that "approximate" is the relative size only; each package has specific details that differ from others, check the specs to be sure.

Photos of the relative sizes can be found here:

The blue parts are 0402, the LEDs are 0603. The two transistors are sot-323 and sot-416. The grid is 1/16".

Other cross references from my notes (mm is lead-lead, not pitch):

SOT-23 1.9 mm mini 3P 1.9 mm SC-59 1.9 mm SOT-143 1.9 mm

S-mini 3P 1.3 mm SC-70 1.3 mm SC-88A 1.3 mm SOT-323 1.3 mm

SC-75 1.0 mm SOT-416 SOT-523 1.0 mm SS-mini 3P 1.0 mm (chiplead, not gull-wing)

SSS-mini 3P 0.8 mm (chiplead)

Then you get into CSPs (i.e. micro-bga style).

SOT-323 is a massive boulder :-)

Those are indeed nice. Anything more than two was a disappointment so far. Found some nice quads wired up in an H-bridge. But they almost wanted a whopping $1 for these in qties. No way, I can do that for under

In the past I found that the sales of 6-7 transistor arrays were a bit of a closed market. Hard to buy and really only available from Asian sources. Which might be ok for designs that are produced in China, as long as the arrays cost 10c or less and come in TSSOP or smaller.

BTW, what's up with Digikey? Fails a lot, saying "server is currently updated", then comes back after a minute or so. Is everything freezing up there?

Do you think SC-75 is here to stay? That would at least yield a factor of two improvement over SOT23, roughly.

Nice! Looks like a bit much in solder. Try Kester 15mil and a Weller ETS tip. Probably I'll have to find even smaller solder soon. Plus a nice USB camera if there is one that can be fitted with a zoom lens (macro is too close to the iron). I don't like microscopes much and the 3x glasses in the lab aren't going to cut it anymore for 0201.

I always wondered why they splintered up the descriptors so badly. Couldn't agree, I guess. Like with those dreaded EU and US differences in resistor sizes that can easily cause costly purchasing mistakes.

Gotta limit yourself to ULN2003-alikes :-).

They recently revamped the search engine. I see some good from the revamp, but it frustrates the hell out of me that every value is now specified to 4 or 5 significant digits! Like we'd have to tell the

Tim.

There are enough footprints in that size, and the cost is comparable. I think it's here to stay. IMHO the SSS-mini is still wait-and-see, perhaps the CSPs will supercede it.

Those were hand soldered with Kester 20mil, with a Metcal 20mil conical tip. Since then I've gotten a syringe of paste, it works even better than wire solder - dab a bit of paste on the pad, place part, heat leads with iron, paste melts.

Most of my close-ups are taken with an IntelPay QX3 microscope. The bigger ones are taken with a digital camera; the Canon A70 has a macro setting that works real well if you put a few layers of paper in front of the flash to reduce the glare.

Other side:

Here are some other photos taken with the QX3:

As for actually soldering, I use a 3.75x mag visor (10 diopter) for the 0201's and 01005's, and a 2.5x (5 diopter) for everything else. I got them from Woodcraft (they're sold for scroll sawing, which I also use them for).

I'm guessing it has to do with lead size, length, etc.

That would be great if SC-75 became a staple. So, might be time to generate the CAD models now.

Good point. Paste is the next thing I want to try out.

Nice job on the chips. Looks like they were done with paste.

I don't like working with something between me and the board while I'd have no problem soldering while looking at a monitor in another direction. But I am in the minority here, most folks at clients don't like to do that at all.

They told me that they had a pipe burst and the hamster got all wet. I am trying to complete an order and it has been really flaky.

Nope. Also hand soldered.

And no mirror server? Oops.

Pipe bursts can be bad. We just had a large retirement home evacuated and they said it'll take 4-6 weeks for restoration of the place.

I've been using SC89 6-pin parts for my dual transistors from ROHM. Still haven't ventured into 0201 parts yet.

On the design I am doing right now I'll be lucky if I can avoid the use of 01005 resistors :-(

Those take me about 20 minutes each to hand solder (place, inspect, solder, inspect, resolder, etc). We've renamed those to "quantum capacitors". One moment they're on the board, the next moment they're gone!

I'll stick to 0201s or 0402s from now on.

Tell me about it. Much of the inspecting effort goes into ascertaining whether it is actually there. Or if not, where the heck it went. Before soldering all it takes is uncle Leroy next door to sneeze and it's gone. One of my clients actually thought that I'd switched to pixie dust.

On Thu, 18 Jan 2007 19:56:55 +0000, Joerg wrote: ...

Everything is "freezing" all over the place these days.

I think it's the fault of U-tube and those "get a date for free" sites.

And blogs, of course. >:-(

Thanks, Rich