Re: TI UC2710 vs. Microchip TC4422 FET drivers

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>


> >
> >And, as far as surface mount goes, once you make
> >the commitment to figuring
> >out how to prototype effectively with SMT devices,
> >you'll find they work a
> >LOT better.  PC boards beat haywired prototypes any
> >day.
> 
> I spend much of my day over a miscroscope using SMT parts for microwave/RF
> circuits.  Have you ever manually soldered in a 0201 size inductor :)  I
> find it a relief to use old fashioned leaded parts in hobby work.

I have soldered some of the tiny parts (although not an 0201)...

I was thinking more of standard SMT ICs with 50 or 25 mil lead pitch. A
decent fine tip (like a Weller PTH or PTO, maybe filed down a bit from the
stock 0.031") on a standard soldering iron will work, and if you are using
the right (read cheap) chips, then rework consists of cutting all leads and
throwing away the part.  A hot plate and a heat gun with a suitable tips
can also work for desoldering (a bit more tedious, but a lot cheaper than $2K).

True, for "spaceflight quality" work, or for large volumes, you DO need the
microscope and hot air rework, vapor phase setup, etc.  But, a decent
magnifying headset(around $25), fine tweezers, and some hypodermic syringes
works just fine. 

It aso helps to not try for ultimate in compact design.. 1206 and 0402
sized parts are fine.  Mostly, the idea is to get your "hobby process
flows" so that you can turn around the board reasonably quickly at low
cost, and use all the nifty chips available these days. I'm also a BIG fan
of the eval boards available for most parts.  Nothing says you can't do
some trace cutting, etc. on the boards.

Unless you need a wire bonder and are working with bare dice, I would think
that you could get everything you need for SMT prototyping for under $500,
brand new.  Scrounged at hamfests and surplus, much, much cheaper. The run
of the mill WTCPT soldering iron will take the SMT adapters ($16 for the
SMTA-7) and then the various SMT tips (around $20-30 each).


The one SMT peculiar thing you ARE going to need is syringes of solder
paste, but they're readily available from the suppliers, and you just keep
it in the freezer next to your bench in the garage (next to the cold beer,
right?)

> 
> Doing SMT right requires a decent investment, $1000 for a good microscope
> (unless you enjoy headaches every day), $2000 and up for a hot-air rework
> station, solder paste dispensers, etc.  Now with low frequency Tesla type
> work, you could get away with large pads and use regular solder and iron.
> For me, low freq is anything below 500Mhz :)
> 
> Rob.