I want a lot of these:
It probably doesn't exist. Maybe a Swiss screw machine company could make us a bucket full of these.
Six of these would press into a small PCB, which could then be bolted onto the bottom of a bigger PCB.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I guess you've already looked at what these guys offer?
In particular the broaching studs.
With the one you have drawn the PTH has to take all the force, the broaching studs put the force into the PCB.
Screws? Press-ins? Your manufacturing people are going to be screeching when they discover you could've designed a thing with snap type standoffs instead!
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website:
Not quite what you asked for but how about getting some threaded bar and turning down to the other size and using a nut to make the collar. Or don't turn it down at all and use a larger countersunk screw.
If you did it in copper or brass then they could be soldered in to the daughter board and so wouldn't need to be a tight press fit.
Does it really need 6 of these supports? I don't envy production putting it together. Wouldn't 3 or 4 thicker ones be much easier to assemble?
-- Regards, Martin Brown
how do you prevent them from pulling out when the nut is tightened?
--
?
That was my thought, there are reasons why you can't get these off-the-shelf.
Perry's link is most useful.
-- Mike Perkins Video Solutions Ltd www.videosolutions.ltd.uk
Standard mil spec type of fixing in sm pcb. not sure about 032 though....
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Right, I've got one place where we press fit pem nuts into pcb. (4-40) If they made one that was 2-56 you could have someone make threaded rod with two threads.
Geogre H.
On Friday, April 20, 2018 at 5:26:17 AM UTC-4, Mike Perkins wrote: .
Try searching on " brass standoffs " on AllpExpress. ( or ebay or Amazon )
Dan
It's going to be a gigantic improvement over Rev A.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Yes, one option would be to delete the knurl and solder one end. I want the botton of the baby board to be essentially planar, but a little solder bump would probably be OK.
They are electrical connections too. I need six connections between boards. The baby board is about 0.5" on a side.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
The force is on the wider part just above the knurl.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I'd hate to rely on solder for a mechanical connection. I know consumer stuff does it routinely, but we've all seen the reliability problems that result.
NT
The old Radio Amateur's Handbook admonished against using solder as mechanical support. Then Tektronix did it everywhere in their old tube scopes.
Paul Revere soldered the handles onto teapots. Who is going to argue with Paul Revere?
-- John Larkin Highland Technology, Inc lunatic fringe electronics
The screw head would probably stick up too far for you if a bump of solder is your limit, but you could put a 0-80 x 1/4" screw through the baby board and tighten down a nut with a drop of blue loctite to hold it. That takes the place of the knurling and pressing and machined end of your stud, then insert through your main board and put on six more nuts. If these 6 screws are all within a 3/8" square then little height differences might be enough to put in some significant bending stresses, causing cracks or bad connections over time. Hmm, browsing at
-- Regards, Carl Ijames
I guess I could just smash the boards together with six nuts and bolts. That's inelegant but easy. I'd have the screw heads poking out the bottom of the baby board, so I'd have to live with that. I would want low screw head height.
The parts on the baby board will get hot. The baby board pushes against a silicone gap-pad that conducts heat into an aluminum baseplate. Some of the gap-pad material is very compliant, about like chewing gum, so would flow around the screw heads and make a decent thermal interface. I could use thermally conductive putty, but that's messy.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
On Apr 20, 2018, John Larkin wrote (in article):
Probably was a better grade of solder, on components that could take the stress, on ceramic terminal strips.
Tube scopes built this way could be washed down in a bathtub with TSP in hot water. Cleaned all the dust and grime off the high-voltage paths.
Paul Revere probably hard-soldered the handles on, using a silver brazing alloy at a red heat. He will not have used soft solder (tin-lead alloy well below red heat). Silver brazing is almost as strong as the base silver metal, and so is equivalent to welding.
. Circling back, my instinct is that pressing these pins in will not prove reliable, mechanically or electrically, for multiple reasons. Temperature cycling in particular may cause self-disassembly. What may work is a plated-through hole with a split steel wire, to accomodate mechanical tolerances and temperature change. Here is a white paper:
.Do you have any Mechanical Engineers on staff? I?d be talking to them.
Joe Gwinn
Solderable? In 0-80 brass might be too soft and will bend. 0-80 in tin plated steel would probably hold together.
The 0.020" flange is rather thin and will be flimsy. It's more like foil and can't be cold headed.
The OD on a 0-80 thread is 0.060". The flange is 0.080" dia, leaving a 0.010" wide flange. That will not stop the part from being pushed into the PCB hole. Tightening the nut or whatever is used on the threaded part will strip the 0.010" wide flange off at almost any torque. The 0.080" flange needs to be much wider. Draw the part to scale and I think you'll see the design problems.
Welcome to micro-threading. Maybe call a supplier and see what they recommend:
Ummm... may I propose an alternative? 0-80 is too small. Instead a flat or pan head 2-56 or 4-40 screw goes through a hole in the PCB. A threaded standoff is screwed onto the 2-56 or 4-40 screw to provide a spacer and support for the other PCB. Washers, lock washer, and nut to complete the sandwich.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Flat head 2-56 screw. 0-80 is too small. Countersink the PCB to match the head. Maybe epoxy to hold in place.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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