On 7/9/21 10:02 AM, Justin Poirier wrote:
If you're looking for cheap, these aren't them! These are anything but
cheap. They're gold-plated Mill-Max pins, 12 cents each, but since I
build these in batches of 25 units at a time or so, ordering them 700 at
a time gets them down to the 5 cents/each price range. Still not cheap,
but I am a huge believer in quality if I'm selling something, so I
really like the flanges that they have for stress relief. If I was doing
this for "just me" I would go get some 24 gauge gold-plated steel craft
wire at Michaels craft store and cut it into 3/8" pieces and solder away.
I am so with you on using plain wire for dip-pcb legs now. Only thought
of it about a year ago and wasn't sure the right kind of wire was
something you could buy.
Out of the 3 methods I've seen so far that attain a result I like (thin
legs that don't violate the specs of any sockets, low profile with no
huge shoulder or insulator) wire is now my favorite for practicality.
I started to try to write up the different good methods, since both the
wire and the leadframe methods need a little explaining. Also just to
provide a place to put links to the obscure parts & materials for
reference, like the fact that mill-max is not the only one that makes
those micro-pins, there is also a Keystone part that's identical. Same
price so it makes no difference, but say the mill-max were out of stock
or something one day.
https://github.com/bkw777/Model_T_RAM/blob/main/doc/DIP_PCB_legs.md
(Actually I should add a 4th option in there. Jeff Birt uses a
particular type of male/female dupont header extension or riser, often
found sold along with raspberry pi and arduino stuff, that happens to be
made from stamped sheet brass, so the legs are thinner than normal
square pins, still a bit thick but thin enough it's not really hurting
anything, although, I don't know if they fit into machined round
sockets. It's a perfectly good method at least for leaf sockets. The
legs are long and you just cut away and discard the female top.)
I arrived at 26 gauge from looking at datasheets for sockets and dip
chips, and there is no worry about brass wire hurting flush cutters or
sockets. I think 24 guage is still fine but I think steel is too hard
and will scratch the plating on the socket.
Strength has been fine, same as any other leg, which are always just
copper or phosphor bronze normally anyway.
I just wish there was a less ambiguous way to find the wire to put into
a doc like that. I have a few links in that doc but 2 out of the 3 are
etsy sellers. In the picture of the first few samples of wire I found
myself, one turned out to be thinner than advertised, and one was just
an ebay listing that is gone now and that same businesses normal web
site does not list that product. There's nothing good like an Amazon or
DigiKey link. There is some on Amazon but overpriced. There are more
dependable links to the suppliers that the etsy sellers are getting it
from, but you can't buy 1 or 5 feet from them. One of the reasons to
even use wire is because it works out a lot cheaper than manufactured
individual pins. But if the wire is overpriced, then you might as well
use the mill-max pins.
--
bkw
