SMA edge mount jacks - Page 1
Forum section: electronics / rf-microwave

author: Zeyneb
author_rank: Regular Contributor
timestamp: November 10, 2020, 04:54:43 pm
content: Hi there,I’m designing a board with an FPGA. I think I want to equip this board with some SMA edge mount jacks.I think you are familiar with those SMA edge mount connector jacks, see picture below. This example is the Cinch 142-0711-821. A gold plated brass one designed for a 1.57 mm thick PCB.I was wondering would it be possible to hand solder these things? I do have an 80W Weller soldering station. And the standard 60/40 tin-lead solder.I understand I need to make a decent footprint to maintain the 50ohm property in the transition from the coax to the microstrip.Would it be realistic to hand solder these things? Please share your comments and caveats.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 10, 2020, 05:00:11 pm
content: I only hand-solder those ones; never had an issue with it up to the 13cm band

author: fourfathom
author_rank: Super Contributor
timestamp: November 10, 2020, 05:19:18 pm
content: Yes, it's entirely practical. I do it all the time, on hand-cut double-sided boards (for small-scale prototyping), and on fabbed circuit boards from JLCPCB and other shops. Any reasonably powerful iron will work, you need to heat up a lot of metal. Liquid flux seems to help, but as long as the surfaces are bright regular cored solder also works well.

author: Zeyneb
author_rank: Regular Contributor
timestamp: November 10, 2020, 05:26:48 pm
content: Thanks, good to know. I added liquid flux to my mouser/digikey Excel shopping list.

author: james_s
author_rank: Super Contributor
timestamp: November 10, 2020, 06:05:51 pm
content: They're easy to hand solder, no additional flux should be needed.I even hand solder them on bare copperclad for deadbug style prototyping, they work very well for that since you can solder them on top of the board and the center pin is then floating above the ground plane and provides a secure attachment point for an input or output.

author: ejeffrey
author_rank: Super Contributor
timestamp: November 10, 2020, 11:20:15 pm
content: Yeah, I hand solder these all the time.I generally use hot air to preheat the board if I have it available. That makes it faster and easier but is by no means necessary if you have a moderately powerful iron and a good tip.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 10, 2020, 11:59:43 pm
content: can you count how many i hand soldered those onthis projectalone? this is where the cheap 30W (130W boost) soldering iron makes wonder.

author: Andrey_irk
author_rank: Regular Contributor
timestamp: November 12, 2020, 03:37:37 am
content: Quote from: Zeyneb on November 10, 2020, 04:54:43 pmWhen soldering them in, make sure the connector's insulator at the back of the board is covered by the tin. Don't be afraid to put too much solder to do that. This makes the high frequency response much better. As for the center conductor - generally you need as little solder there as possible.I don't know what your maximum frequency is, but even the cheapest connectors of this type that I found on aliexpress were pretty good up to about 5GHz.Good luck!

author: hagster
author_rank: Frequent Contributor
timestamp: November 12, 2020, 04:52:16 am
content: Yes, easy to solder.I am a fan of these mid mount connectors. Much stronger and better at high frequencies. Also easy to hand solder and much better for pick and place.https://uk.rs-online.com/mobile/p/coaxial-connectors/8194147/You get even better high freq match by also soldering the bottom on all 3 edges.

author: cncjerry
author_rank: Unknown
timestamp: November 12, 2020, 08:53:34 am
content: I use low temp solder made by chipquik, I think it is, comes as a rework paste, makes it easier. Never had a solder joint break.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 12, 2020, 12:26:34 pm
content: depending on the frequency in use I'd recommend some flux to avoid tin whiskers which could influence the RF properties in an inappropriate way; but that's no issue for f<1GHz