Zener diodes in TO220 or similar?

Really?

:-))

Who said anything about machining? I just meant solder the thing directly between the C-B leads, as if they were huge SMT pads.

He is talking about a TO-220, isn't he?

Thanks, Rich

My experience, devolving from power circuits, was the reverse. The adoption of smd was gradual, with wave-side being the first option as it required only (!) careful design and the purchase of placement and adhesive dispensing hardware. Thermal profiles are actually more easily controled in a wave situation. Reflow was used eventually for higher-density control and interface circuits.

RL

There's no reason why the power need be dissipated in the semiconductor. A small signal zener/active reference and less beefy semiconductor can dump the energy into passive components, over a certain range, if the response requirement isn't too critical. Capacitors can assist the latter limitation.

RL

Back then I worked for a US company but in Europe. Over there the transition to SMT happened earlier and faster. Basically my very first design on the job that I started in 1986 was a huge board, nearly 100% SMT. The only non-SMT parts were a few electrolytics because I had no faith in tantalums. Turns out that tantalum paranoia had a very good reason and was a good thing ...

We had to purchase our own reflow equipment because providers were just coming on line and they had some difficulties tackling our huge boards. I was anticipating lots of problems but to my surprise our production manager who had no prior SMT experience got all this licked without a hitch.

There were some power circuits on there but probably not the level you are dealing with. Things like a few dozen pulsers with a couple of watts each. End of 1989 the German engineering was closed and self-employed I did design numerous power modules, hundreds of watts. Those were also all reflow soldered. Actually the first SMT wave process I ever encountered was in the US, never saw one over there.

Yeah, looks like I am dumping it into a FET. Looks good on the sim so far. More parts, but works.

So I guess you've never seen dip soldering?

Not in a developed country :-)

Wave soldering, yes, I've seen that but rarely for SMT although I am sure it must have existed for that even in Europe. Reflow is so much nicer and cleaner. Boards get loaded, big mushroom button is pressed, a gentle hiss and they all trudge through an incubator-like glass tunnel.

A quick dip in dilute HCl shines them right up.

Yeah, mine are like that. They are great for, say, the power connections into a hacked-copperclad breadboard. Solder the ground tabs directly to the copper.

John

Old Tektronix ceramic strips are cool too. I scored a bunch at a flea market. Here's some of both:

ftp://66.117.156.8/99A260A3.JPG

John

We have a selective solder machine that gets used for PTH parts. It's essentially a solder fountain on a X-Y stage.

A lot easier before RoHS.

Oh, now you've made us all drool ...

And the OSHA and EPA guys didn't flinch?

Luckily only two or three of my designs had to be RoHS, have to look. What ticks me off is that non-RoHS is now a custom process even at some US fabs. Got a quote last week for the next design and the tooling fees were waived for RoHS but not for leaded. Although I always call them and haggle that away :-)

Yup, I've got a baggie of those, too (removed I think... gunky).

Tim

RoHS? CE? ISO9000?

Nope.

John

Evidently not. It uses a lot of lead too. ;-)

We've run into that as well. Some of our stuff is RoHS, some not. We're moving in the RoHS direction but using leaded inventory up on the products that don't have to be RoHS.

Selling to Europeons, yep. Customer demands, yep. UL, CB, and all that crap too.

Nope, though don't give the boss any ideas.

Keystone still makes them: