Wirewrapping on the cheap - pin headers. - Page 1
Forum section: electronics / projects

author: ChristofferB
author_rank: Frequent Contributor
timestamp: May 04, 2015, 12:04:50 pm
content: I've previously tried this out, with no further problems, but I'd like to hear it from people who know what they're doing.Wirewrap IC sockets are massively more expensive than regular IC sockets, and the prices seem to be consistent across most places that sell them. This probably, in part, because the legs are more precisely manufactured; they're very sharp edged, the corners, to allow the wrapping to cut through oxidation and greases etc.So i was thinking: Is regular pin headers (also square) "good enough" to make a decent wire wrap connection? If so, that would allow the use of IC pattern protoboard, with cheap sockets soldered in, along with header rows. This would be same-side wire-wrap, of course.I've done this for a Z80 processor board once, but I never got it working (most likely for other reasons).Of course it will have higher contact resistance than a proper wrap pin, but since wire-wrap still has lower contact resistance than a traditional solder joint, would it still, presumably, be acceptable?-The problem of shorter pins is not an issue, at least, one could just use double row headers. (a std. header pin will hold two wraps nicely, btw).This is the board i made with this system, for a general idea of what the method will look like, and because threads with pictures are better than threads without:

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 05, 2015, 10:26:11 pm
content: Hi ChristofferB,With traditional wire wrap IC sockets the wire wrapping would be on the non component side of the board where you had to constantly flip between each side of the board to tracing through a circuit.With your technique most of the wiring is on top of the board which is a lot easier to trace through.I would use the gold plated pin headers as this would reduce oxidation with the wire wrap joint.Wire wrap for a prototype is ok but if it’s going to be used for a long period of time I would solder the wire wrap joints once you finalized the layout this would improve its reliability.Your technique looks good to me its alot better than using bread board were you push wires into holes.HalfSpace

author: tggzzz
author_rank: Super Contributor
timestamp: May 05, 2015, 11:18:38 pm
content: Quote from: HalfSpace on May 05, 2015, 10:26:11 pmProperly done wire wrap is suprisingly robust, and was perfectly suitable for production.QuoteOh, either you are samning with faint praise, or you are giving solderless breadboards too much benefit of the doubt

author: SL4P
author_rank: Super Contributor
timestamp: May 05, 2015, 11:30:37 pm
content: The later wire-wrap technology was pretty clever.Using thecorrectwire, tools and pins --- (none of them cheap*)No need to strip the wire, wrap directly onto the pins, and get a 'better than soldered' moisture-resistant connection sealed under the wire's 'kynar' insulation!The molecular bond at the corners of the square pin were as good as it gets.The big deal with higher voltage/frequency projects is the maze of spaghetti and crosstalk.Kynar ==https://en.wikipedia.org/wiki/Polyvinylidene_fluoride* I still have wire and tools I purchased 35 years ago...!

author: coppice
author_rank: Super Contributor
timestamp: May 06, 2015, 01:48:02 am
content: Quote from: HalfSpace on May 05, 2015, 10:26:11 pmA properly wire wrapped joint is massively more reliable than any soldered joint. Various statistics say 100 to 1000 times more reliable. The reliability weakness with wire wrap was the need to use IC sockets, not the wire wrap joints themselves.

author: Fungus
author_rank: Super Contributor
timestamp: May 06, 2015, 10:13:43 am
content: Quote from: coppice on May 06, 2015, 01:48:02 amAndno true Scotsmanwould wire wrap...

author: ChristofferB
author_rank: Frequent Contributor
timestamp: May 06, 2015, 01:00:58 pm
content: Thanks for the replies! There actually existed wirewrap sockets with pins on the same side as the components, or boards that were made like that. I've sumbled across one problem with the idea:Regular headers aren't long enough for two modified wrap connections, you'd have to use dual line headers. Using my old "non-modified" as in, without two/three loops of insulated wire, just fits two wrappings. I don't have a resistance meter that precise to measure contact resistance, but I'll write a conclusion on the method when the project is done.

author: coppice
author_rank: Super Contributor
timestamp: May 06, 2015, 01:29:47 pm
content: Quote from: Fungus on May 06, 2015, 10:13:43 amHow does a statement of research results become a no true Scotsman fallacy?

author: ChristofferB
author_rank: Frequent Contributor
timestamp: May 10, 2015, 01:49:51 pm
content: Sorry to bump a somewhat old thread, but I wanted to write some concluding thoughts on the method, now that the project is near done.It can be done way neater than the original photo I posted (I think it's the first wire wrapped board I did), as the pic of the new board will show.So far I've encountered some minor issues, but the benefits make it very worthwhile, I think.Cons:- Difficult to use modified wrapping (with some turns of insulated wire) - might just be my tool.- Fits only two wrappings per pin, could use dual row headers if needed.- Tight fit between IC socket and pin for the wrapping tool. when soldering in the headers, tilt them slightly outwards.-probablynot as low contact resistance as a professional socket (not tested) - but it didn't have an impact on the circuit.Pros:- VERY VERY cheap. a 40 pin socket cost me around a dollar, headers and all. as opposed to 10-20 USD per 40 pin wire wrap socket.- Low profile: only the fraction of height of a wire wrap socket- Can be mounted on same side as IC, aids the layout and wrap process significantly.- Socket and headers IDEAL for IC pattern prototype boards.All in all, I'm pretty happy with it. You can get long pin headers, so you could essentially make pins the same length as wire wrap pins, but i kinda like the low profile of the circuit board.Hope some will find this useful--Christoffer

author: retrolefty
author_rank: Super Contributor
timestamp: May 10, 2015, 06:15:02 pm
content: Quote from: tggzzz on May 05, 2015, 11:18:38 pmI worked for a mini-computer company in the 70s. We sold an optional hardware floating point processor board. We didn't sell that many of them so a PCB was never spun, just a large 15"X15" protoboard filled to all corners with wire wrapped sockets, maybe 400 ICs or so, I forget. This was a very heavy board but beyond that I never saw a failure in the field.

author: stockvu
author_rank: Newbie
timestamp: April 13, 2019, 04:25:40 pm
content: Let me chime in for those who read this topic later.I've used traditional wire-wrap and had the same problems with cost and availability as the OP. I like what the OP shows in his pictures. That's a slick way to build resilient circuits!In my situation, I tried wire-wrapping thru-hole headers inserted intosolderless breadboards. For me, this was a good way to get somewhere for reasonable time and cost. Then I discovered you could make plug-ablecablesusing headers and wire-wrap too!This meant not using jumpers (aka push wires) which eliminated intermittents and rats nest issues!I wrote a website about this wiring technique (search forpermanent solderlessif you're interested).However, I found there arestrict rulesone must abide by to sidestep problems using the above tactic.FWIW