Re: Really small SMT: Popular packages?

DJ Delorie wrote:

Joerg <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> writes:

After getting used to 0402 and 0201 passives it seems my next design
has to also shrink for the transistors, this time all of them. I have
designed in things like SC-75 in the past but there is quite a
bewildering number of choices in the "below SOT-23" category.


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.


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


Photos of the relative sizes can be found here:

http://www.delorie.com/pcb/smd-challenge/mine-back.jpg


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.


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).


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.

--
Regards, Joerg

http://www.analogconsultants.com
.