Correct soldering for double-sided boards? - Page 1
Forum section: electronics / beginners

author: elroy
author_rank: Regular Contributor
timestamp: October 21, 2017, 05:31:11 am
content: I'm getting ready to assemble the first kit I've done in a long time. Although it's very simple, I noticed that printed circuit boards have gotten more sophisticated than the last time I looked. In particular, this appears to me to be a double-sided board, with traces and soldering rings on both the top and bottom (see pictures below).So my question is this. If I insert the leads through the holes and solder them on the bottom side as I'd do with a traditional PCB, can I assume the solder will flow adequately to make good contacts? Or do I need to take special care to make sure that the solder joins the lead to the board on both the top and bottom sides?

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: October 21, 2017, 05:42:43 am
content: The majority of double sided boards are through-hole plated, in which case you solder the reverse side only. It's always a good idea to inspect the upper side to see that solder has penetrated the holes though.

author: David Hess
author_rank: Super Contributor
timestamp: October 21, 2017, 05:45:37 am
content: There should be no problem soldering from one side which is usually the bottom; at least I have never had a problem with this. If the board and parts are new, then no clean solder which has a less aggressive flux will work. If the board and parts are old, then a solder with a fully activated flux is a good idea.

author: Shock
author_rank: Super Contributor
timestamp: October 21, 2017, 08:21:03 am
content: A perfect joint would have a concave fillet on both the component side and the underside of the board. You need to have a clean PCB and component leads, good solder and flux and the right amount of heat and solder applied.

author: frog
author_rank: Contributor
timestamp: October 21, 2017, 08:37:14 am
content: The PCB is clearly PTH (plated through hole) and so there's conduction between the top and bottom layers. For high currents you'll need to consider the conductivity of the PTHs themselves, but for day-to-day stuff it's safe to assume that if it's soldered on one side then it's good.

author: ElektroQuark
author_rank: Unknown
timestamp: October 21, 2017, 09:03:29 am
content: The solder will flow through the hole and will fill it, don't worry.Only in the case the lead fits tight in the hole could the solder not flow.

author: Awesome14
author_rank: Regular Contributor
timestamp: October 21, 2017, 09:36:13 am
content: Just experiment with a few joints. Don't overdo it.

author: tooki
author_rank: Super Contributor
timestamp: October 21, 2017, 05:48:40 pm
content: Quote from: elroy on October 21, 2017, 05:31:11 amGo on YouTube and look for thePACE Worldwide soldering videos.Episode 6 is specifically about components (which given the age of the videos is mostly through-hole), but I suggest watching them from the beginning.In any case, plated through-holes solder easily. The main thing to remember is to dwell on the pinslightlylonger, because as the hole heats all the way through, suddenly capillary action will draw solder to the other side, and you may need to add a smidgen more.

author: ebclr
author_rank: Super Contributor
timestamp: October 22, 2017, 12:25:08 pm
content: Outdated, but amazing

author: elroy
author_rank: Regular Contributor
timestamp: October 22, 2017, 03:20:47 pm
content: Quote from: tooki on October 21, 2017, 05:48:40 pmThanks! A helpful refresher, and took me right back to 1980.

author: tooki
author_rank: Super Contributor
timestamp: October 22, 2017, 04:16:18 pm
content: Quote from: elroy on October 22, 2017, 03:20:47 pmI know, right?? Apparently, the host of that series was a DC-area newscaster or weatherman, which means I probably saw him on TV as a kid! (My aunt used to live in Silver Spring, MD, where Pace has or had their HQ or a satellite office, as seen on the address on the PCBs in the videos!)

author: BMack
author_rank: Regular Contributor
timestamp: October 23, 2017, 04:04:54 am
content: Honestly, soldering well isn't difficult. If you're asking these questions, you've probably been researching and that means you're probably a lot better than most in soldering already. It's the people that don't ask and don't try to learn that do terrible jobs soldering.

author: elroy
author_rank: Regular Contributor
timestamp: October 23, 2017, 08:09:36 pm
content: Thanks. I soldered for many years, but not too much recently, and it was just that double-sided boards were a technology I didn't yet have any experience with. I'm happy to report that this project went fine, and the kit is functioning perfectly.