Apollo Saturn V LVDC Board Teardown!!!!!!!

Pins are soldered to the hybrid substrate, and then the pins are welded to the PC board. Somehow the welding did not melt the pins off the substrate. (???)

Spot welded? (I'll watch later)

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

But what temperature would that be at?

Well.. welding is welding, yes, but you get very different results between highly localized and loosely generalized heating methods. In order of HAZ (heat affected zone) size, smallest to largest: e-beam, laser, spot, arc, torch, friction, induction, forge. (Give or take various considerations for each process, but I think this is a pretty typical ordering.)

E-beam and laser do highly localized heating (down to the micron), with e-beam having more penetration I would think (an electron beam as high as ~1MeV can shoot, I think, a milimeter or so into solid metal?).

Spot welding is a traditional thermal method, but it's heatsinked with solid copper electrodes, and done in a relatively short pulse (

Thank you. Friction is the one whose existence I learned of most recently.

I'm sure we can narrow it down to the first 3.

I assumed even spot welding would have melted the solder 2mm away.

So how do you think those pins were welded by IBM in 1968?

I spent a year there one day.

Pins are brazed within the ceramic form. Internal bonds are stitch-bond gold or Al wire to pad, high temperature solder between substrate and sputter/print patterned ceramic.

Ceramic carrier is simply reflowed to printed wiring.

RL

See the video. IBM welded the pins to the board without solder, but the pins are soldered to the hybrid 2mm away.

If this is the same technology as some other stitch-bond gear, it is done by ultrasonic welding, and pretty fast. I've also seen boards that were a bit like wire-wrap, the chips were welded to fat, round pins that stuck above the board on both sides. The pins were maybe .050" diameter. Then, on the other side, the wires were ultrasonically welded to the pins, right through the insulation.

Jon

Didn't watch the video. This machine doesn't even have sound.

You wouldn't solder pins to the ceramic without mech support. 'Modern' commercial hybrids count on c-clip attachment for inline side attach - older ones were brazed.

I suppose you could attach an IC to the board any way you pleased. Spot welding would be good, if you could do it right every time and had the budget.

The combination you suggest was used isn't impossible, or bad, it's just uncoordinated. As an FRU, it's a throw-away item anyways, if it shows signs of misbehavior.

RL

These pins had c-clips on the edges of the hybrids. IBM used the latest methods they had, in advance of using the same devices in the 360.

"Ceramic" is scary. Are you sure there's no Beryllium, etc.?