RF relays

That would also require a big stereo with lots of blue LED light and speakers the size of the rear bench.

Once I had a guy with a VW Beetle like that pull up next to me. Flames painted onto the side, teeny front wheels, big fat rear tires. Rap music, tchk .. tchk .. *BOOM .... tchk .. tchk .. *BOOM, really loud. I looked over and the guy in there was at least 70.

Wouldn't a drill hole have to be pretty big such that surface tension wouldn't be a problem?

I think the industry gave up and just leaves it there.

snipped-for-privacy@attt.bizz a écrit :

Not everybody do that. I've a customer who, after thorough cleaning after thorough US cleaning have the final pass with... a steam generator and a specially made nozzle... Now, that's clean. And he doesn't use that dreaded 'no clean'...

One thing perplexes me: Do you really need a 50 Gohm resistor, or can one use a Pi or T circuit with equivalent transmission, and in either case, why or why not?

Joe Gwinn

Joseph Gwinn a écrit :

The current noise of a 1G resistor + 1:50 divider is sqrt(50)=7 time higher than for the 50G resistor.

Phil, is your 1G resistor needed for higher BW or for a gigantic 5~10nA input current?

If the solvent can get under there, then enough agitation should get the flux out.

Cheers

Phil Hobbs

Plan A: I sometimes build prototypes by using cyanoacrylate adhesive to glue parts to the PCB before soldering. The glue would plug up the tunnel under the components preventing the flux from entering. However, cycanoacrylate glue is hygroscopic, so that won't work for your application. Instead, perhaps some wax to tack the part in place and plug the tunnel? The heat from soldering should melt the wax, thus clearing the tunnel. The actual solder connection is at the ends of the SMT component, far away from the wax plug. Instead of wax, a narrow strip of Teflon tape to plug up the hole might work. Just pull it out after soldering.

Disclaimer: I haven't tried any of this (yet).

Plan B: Use a clear glass PCB. High resistivity and cool looking for the publicity photos. However, it also allows for easy visual inspection of the BOTTOM of SMT components. While cleaning out the trapped flux is a PITA, it can be made easier if you can see what you're doing.

Plan C: Swage some gold pins into the PCB and solder the components above the PCB. Extra credit for using Teflon standoffs, in the manner that was popular in the 1950's.

It's to allow a bit of flexibility to trade off speed vs sensitivity.

Cheers

Phil Hobbs

But the flux was put there before the component and it was a lot hotter between. If the remover can't get through the hole it can't even get to the flux.

Am 01.02.2013 19:39, schrieb Joerg:

It was the Keithley 480 Picoammeter. Here's a link to EEVblog (27 min 30 sec):

Regards, Alexander

I'm not an expert at board cleaning, but for aqueous processes surface tension pretty much goes away with a bit of surfactant (i.e. detergent). Ultrasonicating helps a lot too. For this purpose, even if it needs

I'll try the 4-oz copper trick as well, to try to get a bit of actual flow under the parts. I'd love to avoid using hot hydrogen atmosphere for reflow, but that would probably be okay too, if it meant we met our leakage spec. It's mainly the 1/f noise of the leakage that I care about.

Cheers

Phil

we

Rosin flux and solvent wash will give > 14gohm, all I can measure. Aqueous is a production disaster for low leakage apps.

How about using an RC servo to move a pogo pin?

Yes, that's the one. Phil, check this out, worth it.

More specifically, two pogo pins with a 1G resistor between them.

:-)

-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

We used a citrus based cleaner in an automated board washer. That was followed by an alcohol bath if it needed extra cleaning. Unfortunately the ME that set the thing up has passed away, so I can't ask him any questions.

Damned spellchecker. I typed in Buss Bar as one word. I looked to make sure it was spelled right, and it changed it.

Haha, nice.