USB microscopes for very small SMT

Tin? A lot of ours were milled out of 1/2" aluminum sheet. The older designs were in custom aluminum boxes with threaded inserts for the board mounts & feedthroughs.

We've got to stop being this wasteful with our resources. Except for situations where mechanical precision is important (optics, injections pumps, and such) there is usually no reason to use milled material.

You're forgetting microwave filters (and other things) there... anything that has to handle any decent amount of power is often something like a bunch of coupled cavity resonators, all nicely milled out of a chunk of aluminum and then plated. Or heck, even invar or kovar for those really demanding applications where money is no limit!

We have all of one product that uses a milled case... it's a wideband isolation amplifier, and I believe the rationale for the milled case was that it contains a handful of shielded sections, and it was cheaper to just CNC mill out the cases to create each shieled area than to have someone custom cut (or chemically etch) some tin and then pay our guys to sit there installing the individual shields (and either solder or otherwise create solid seams).

Did you see that photo of the Tektronix SD20 guts that John posted? Beautiful milled case there... ;-)

---Joel

Ok, that falls under "needs mechanical precision". Although until recently I had a tunable oscillator in the lab. Projetado e fabricado no Brasil, cheap steel, most holes drilled willy-nilly and screws force-jammed into them, none of the holes seemed to lined up, looked horrible inside. Yet it was super stable. Hats off to the designers (but not to the production guys).

I suggest to really price that out. Unless it is a very low volume product simple steel constructions can be remarkably cheap. I convinced several clients to ditch their aluminum card cages and do custom steel. Same for milled parts. Some thought this was going to cost a lot, only to learn that it was actually cheaper, not any heavier, and almost turned their equipment into a tank.

No, only the creme brulee post. Almost made me trudge over to the fridge again where the gingerbread is. If it was on a.b.s.e. that's history for me. My ISP pulled binaries because of an overzealous AG (we all know who that is).

Beautiful

ftp://jjlarkin.lmi.net/SD20.zip

and here's my sampler...

ftp://jjlarkin.lmi.net/Sampler1.JPG

John

Beautiful

That looks freaking expensive. I am surprised they still use milled material.

Neato! But the copper clad looks like whoever soldered it together had half a pack of Marlboros right next to the board ;-)

Beautiful

Gold plated, no less. The SD20 sold for $4840 in 1998.

I etched and soldered that myself. Dual-channel (only one stuffed) half-bridge sampler, with symmetric sampling impulses generated by an SRD and shorted transmission lines. Got 5 GHz analog bandwidth. I'd love to go into the sampling scope business, but it's hard to compete with ebay.

John

Beautiful

Ouch. I guess those days are almost over now. Except for clients such as large research labs that always seem to have oodles of money at year end.

Just doing my little year-end Digikey order. Sez no DHL pickup today on account of the weather. Must be tough out there.

But you could make and sell little TDR boxes :-)

We didn't build throwaway equipment. Some has seen well over 30 years of continuous service. Also, the milled design was not only smaller, the milled housing carried away the heat. We built microwave equipment, where the housing figured into the overall performance. If we used a cheaper housing, we had to add a lot of parts to stabilize the design. A cheaper housing was tested for out low phase noise synthesizer. They stayed with the nickel plated design with a DB 25 connector and over 30 soldered in feed through capacitors, because the new case had too many stray currents that affected phase noise.

A CNC machine can spit out milled aluminum parts for less than some sheet metal designs can be cut & folded. The aluminum chips are collected, and reused, so there is little waste. If it was a high volume part it would be cast, then milled but most of ours were bought at 100 or less at a time.

Beautiful

I heard on the news that DHL was shutting down its US operation.

Beautiful

AFAIK that may not affect international shipments (yet).

For that kind of gear it is sometimes ok. The first design I took part in after my masters degree was an ultrasound machine. I still see them popping up at used med gear dealers. Those things last, despite not being made of milled stuff.

Stray currents? That usually points to some design issues. I've helped ham radio folks build microwave stuff in "Danish Butter Cookies" tin cans. Worked marvelously but was very bad for our wastelines because the original contents had be eaten.

From an energy point of view still a rather low efficiency process. But it's good that you guys at least re-used the chips. I have seen them being chucked into the garbage.

I haven't ben able to track down a final date. Apparently, they are negotiating with UPS to handle the US end of international shipments, but haven't been able to make a final agreement. I would be leery of them, until things settle down.

This was for deep space telemetry for NASA, not amateur radio service. The low noise floor was one of our best selling features. It was cleaner than some single channel crystal controlled designs. A tin enclosure was thinner, and required the use of PEM fasteners to mount the PC board. Over time, they developed resistance between the different metals. The thicker, nickel plated housing allowed the hardware to be silver soldered, and the stiffer case let us use a Monel gasket. A cheaper case would have dropped the cost less than $25 on a $1000+ module. It was the heart of five of our product lines.

We had it done by a large outside machine shop that recycled all their scrap metals. (Cutting oil, and all.) :) When you generate it by the ton, its foolish to throw it away.

Beautiful

I really should, a tiny USB or Ethernet box, to sell for $1200 maybe. The hardware is dirt cheap and fairly easy; I have a deconvolution algorithm that makes ugly TDR pulses into beautiful TDR pulses, which makes the design a lot easier. The real pain is the software.

John

Beautiful

(Cool board - is the big grey patch just solder or did you do something else to it?)

Well if you will write everything in assembler... :) :)

Beautiful

I just tinned it. The bare copper tarnishes quickly.

What I really need is a stack of copperclad scraps that are gold plated.

Only the embedded stuff. I've done a little "real" Windows programming in PB/Win, and a lot more console-mode stuff in PBCC.

John

Beautiful

Although you could limit the use to non-Vista systems. With respect to Vista I am seeing a widespread non-acceptance among my clients (same in my office).

But if you design one it needs to be absolutely rugged because it's going to be used by cable crews. Out here they usually show up in 4WD trucks with coarse-thread tires, for good reason.

Yeah, I did a lot of nickel plating as well. Not very expensive and otherwise quite excellent. Plating is a regular subject almost every time I receive an EMI emergency call from a new client. Typically it's all anodized because it looks cool, and nothing is conductive :-(

Believe me, some still do it. Sad. It's like dentists chucking old gold crowns. At a billing rate well north of $500/hour I guess it doesn't matter ...