Best way to jump 2.5mm gap between PCBs? - Page 1
Forum section: electronics / projects

author: 3dgeo
author_rank: Frequent Contributor
timestamp: October 13, 2019, 04:38:51 am
content: Hello,I need to find cheap solution to jump from bottom to top PCB (4 contacts, 2 pins below 1A, others logic level, 1.6mm PCB, 2.5 mm gap between PCBs,).For oneoff regular 2.54mm pin header works, but I need better solution for bigger quantities (SMT, PNP).Pogo jumpers like in the picture below would be perfect, but those cost a lot and PNP of them would be expensive as well...All suggestions are welcomeUpdate:I found that batteries connector might be a good solution and those are cheap.These oneslooks promising (even if hand soldering it would not be that labor intensive as pin header):

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: October 13, 2019, 05:27:46 am
content: Watching with interest, and I'll offer a couple of wacky PnP-compatible ideas.FFC connectors are not terribly expensive. It might cost a bit if you need to pay someone to manually insert a flat flex during assembly of one board to the other.Mezzanine connectors like Hirose FC series are available in 2.5mm and several other mated heights, but might not compete too favorably on price with the pogo pins.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 13, 2019, 05:45:51 am
content: Only 4 pins? EMI fingers touching SMT pads may be less eye-watering on cost.Tim

author: Nusa
author_rank: Super Contributor
timestamp: October 13, 2019, 06:18:18 am
content: If they're low power signal connections:https://en.wikipedia.org/wiki/Elastomeric_connector

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 13, 2019, 06:39:49 am
content: Good idea, would work for logic signals. May need to buffer them if you need any speed or current capacity. Depending on how much resistance you get with them. Would still want to see a metallic ground, and same idea with power if needed.Tim

author: 3dgeo
author_rank: Frequent Contributor
timestamp: October 13, 2019, 06:51:13 am
content: Thank you for your input,jhpadjustable, any "two part" connectors are out of the question due to double PNP price and they usually are higher pin count.Well, I actually need two 4 pin jumpers, but I can't make one 8pin connector out of them, they must stay in their current locations.Tim, I was thinking about metal "springs" too, but those are expensive and PNP price for 8 of them will add up in mass.Nusa, I updated main post – 2 pins up to 1A, rest are logic level, don't think your solution will do with my specs.Battery connections I found looks promising, but I need plan B and C, so more ideas please

author: Berni
author_rank: Super Contributor
timestamp: October 13, 2019, 07:55:07 am
content: Just use a low profile board to board connector.One particular family i like is the Hirose DF40:https://www.hirose.com/product/series/DF40?lang=en#They come in a wide range of sizes and mating heights (Including your specific 2.5mm), they have lots of pins, will handle high speed signals and they are pretty cheap for what you get. If you need more current you simply parallel pins together.

author: tooki
author_rank: Super Contributor
timestamp: October 13, 2019, 01:40:24 pm
content: Quote from: 3dgeo on October 13, 2019, 04:38:51 amYou do know that they make SMT pin headers? Take a look at the mill-max catalog, for example.

author: max_torque
author_rank: Super Contributor
timestamp: October 13, 2019, 05:13:40 pm
content: have the boards got to be disassembled after assembly? If not, just use std 0.1" male pin headers, soldered into plated through holes. You can put the plastic spacer part of the pin header on the opposite side of either board, where the components presumably are (and hence probably have more than 2.5mm height available)

author: Wendy_Preston
author_rank: Contributor
timestamp: October 18, 2019, 09:00:10 am
content: Not trying to criticise, but... bit vague on some details here. These are the sort of questions we'd be asking to narrow down which type of connection styles would suit:Number of mating cycles likely in the life of the product?Current per contact?Do you have any room on the other sides of both boards for protruding elements?Any vibration issues, temperature, anything else in the environment to worry about?Any manufacturing process issues , or assembly methodology, to consider?What do you think is the "cheap" price point you are looking for? "Cheap" is relative... and volumes you require will also be a factor in the price you pay.We've got a handful of solutions in our range that would "do the job" with the few bits of information given - from 2.54mm pitch headers, to pogo pins like your picture, to folded spring contacts like the second picture, to terminals and PCB sockets... most could be adapted to your needs, all at different price points and available from different distributors.Here are some catalog sections to have a look at:https://cdn.harwin.com/pdfs/Harwin_PC_EMC_Shielding_Spring_Contacts.pdfhttps://cdn.harwin.com/pdfs/Harwin_PC_Spring_Loaded_Contacts.pdfhttps://cdn.harwin.com/pdfs/Harwin_PC_Connectors_M20.pdfhttps://cdn.harwin.com/pdfs/Harwin_PC_Sockets.pdfhttps://cdn.harwin.com/pdfs/Harwin_PC_PCB_Hardware_Terminals.pdfIf you want to contact one of our technical team for more in-depth assistance, you can emailtechnical@harwin.comanytime. My colleagues will be happy to help!

author: 3dgeo
author_rank: Frequent Contributor
timestamp: October 18, 2019, 10:20:44 am
content: Quote from: Wendy_Preston on October 18, 2019, 09:00:10 amNot trying to criticize, but... alternatives I found are in order of magnitudes cheaper.I did specify current requirements and if there were any more restrictions I would have pointed them out.

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: October 18, 2019, 12:00:00 pm
content: Quote from: 3dgeo on October 18, 2019, 10:20:44 amYou get what you pay forI am not affiliated with harwin in any way, but I have used their connectors on several projects for my hobby and designed some into designs at work, too. Sure, you pay more, but I didn't have any problems regarding reliability, the datasheets are precise, you get usefull 3d models and the telephone support is excelent.Once I searched for a reliable connector which gets actuated very very little (once a year or less), gets exposed to all kind of atmospheres that could potentially build up dirt and grime on the contacts, must work for high current as well as very low current and has to maintain a very low contact resistance. I talked with the support and got an excelent solution. They took their time talking with me, even though I didn't need very high volumes of that thing.That is it worth for me spending a bit more, since I assume I will have less problems that need (expensive) time to fix them if I use good parts to start with.

author: tszaboo
author_rank: Super Contributor
timestamp: October 18, 2019, 02:40:18 pm
content: Standard 2.54mm SMD or TH right angle pins on one board.Same with the header on the other board.Slide them together. The plastic is 2.54 or 2.5mm thick.The pictures are enormous, and I have no ide how to make it smaller.

author: Wendy_Preston
author_rank: Contributor
timestamp: November 01, 2019, 08:21:42 am
content: Quote from: Ysjoelfir on October 18, 2019, 12:00:00 pmThanks for that Ysjoelfir - not trying to say Harwin is the best/only/cheap solution - we are not. The connector industry is enormous with many variations on products, and we're careful not to make any assumptions on specifications that are not mentioned, as we know that Harwin are not always the right fit - hence the additional questions. But if cost is your primary driver, then there are lots of other solutions out there, and I'm sure you'll find something that will do the job perfectly adequately. "Horses for courses" as they say in Britain (not sure how far that translates!). I hope you find exactly what you are looking for, 3dgeo, you have my best wishes in your endeavour.PS The reason I mentioned current, even though you stated the average level, was to consider any additional surges or spikes, these are just the sort of items that we try and consider with our customers.

author: MSS
author_rank: Newbie
timestamp: November 01, 2019, 07:07:08 pm
content: I think board to board connector like this will be good way to solve the problem:https://www.molex.com/molex/products/datasheet.jsp?part=active/0787326021_PCB_HEADERS.xml

author: thm_w
author_rank: Super Contributor
timestamp: November 01, 2019, 10:10:07 pm
content: Quote from: NANDBlog on October 18, 2019, 02:40:18 pmI saw this recently when I took apart a flashlight, its much more compact than I would have thought.I think you can get both in SMD.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: November 01, 2019, 11:31:09 pm
content: Q) Best way to jump 2.5 mm gap between PCBs?A) About 7500 volts.Sorry, couldn't resist